L4 Protein Research Articles

Characterization of linezolid- and methicillin-resistant coagulase-negative staphylococci in a tertiary hospital in China

BackgroundRecently, linezolid-resistant staphylococci have become an emerging problem worldwide. Understanding the mechanisms of resistance, molecular epidemiology and transmission of linezolid-resistant CoNS in hospitals is very important.MethodsThe antimicrobial susceptibilities of all isolates were determined by the microdilution method. The resistance mechanisms and molecular characteristics of the strains were determined using whole-genome sequencing and PCR.ResultsAll the strains were resistant to oxacillin and carried the mecA gene; 13 patients (36.1%) had prior linezolid exposure. Most S. epidermidis and S. hominis isolates were ST22 and ST1, respectively. MLST typing and evolutionary analysis indicated most linezolid-resistant CoNS strains were genetically related. In this study, we revealed that distinct CoNS strains have different mechanisms of linezolid resistance. Among ST22-type S. epidermidis, acquisition of the T2504A and C2534T mutations in the V domain of the 23 S rRNA gene, as well as mutations in the ribosomal proteins L3 (L101V, G152D, and D159Y) and L4 (N158S), were linked to the development of linezolid resistance. In S. cohnii isolates, cfr, S158Y and D159Y mutations in the ribosomal protein L3 were detected. Additionally, emergence of the G2576T mutation and the cfr gene were major causes of linezolid resistance in S. hominis isolates. The cfr gene, G2576T and C2104T mutations, M156T change in L3 protein, and I188S change in L4 protein were found in S. capitis isolates.ConclusionThe emergence of linezolid-resistant CoNS in the environment is concerning because it involves clonal dissemination and frequently coexists with various drug resistance mechanisms.

Persistence and evolution of linezolid- and methicillin-resistant Staphylococcus epidermidis ST2 and ST5 clones in an Italian hospital

Staphylococcus epidermidis is a member of the human skin microbiome. However, in recent decades, multidrug-resistant and hospital-adapted S. epidermidis clones are increasingly involved in severe human infections associated with medical devices and in immunocompromised patients. In 2016, we reported that a linezolid- and methicillin-resistant S. epidermidis ST2 clone, bearing the G2576T mutation, was endemic in an Italian hospital since 2004. This study aimed to retrospectively analyse 34 linezolid- and methicillin-resistant S. epidermidis (LR-MRSE) strains collected from 2018 to 2021 from the same hospital. LR-MRSE were typed by Pulsed-Field Gel Electrophoresis and multilocus sequence typing and screened for transferable linezolid resistance genes. Representative LR-MRSE were subjected to whole-genome sequencing (WGS) and their resistomes, including the presence of ribosomal mechanisms of linezolid resistance and of rpoB gene mutations conferring rifampin resistance, were investigated. ST2 lineage was still prevalent (19/34; 55.9%), but, over time, ST5 clone has been widespread too (15/34; 44.1%). Thirteen of the 34 isolates (38.2%) were positive for the cfr gene. Whole-genome sequencing analysis of relevant LR-MRSE displayed complex resistomes for the presence of several acquired antibiotic resistance genes, including the SCCmec type III (3A) and SCCmec type IV (2B) in ST2 and ST5 isolates, respectively. Bioinformatics and polymerase chain reaction (PCR) mapping also showed a plasmid-location of the cfr gene and the occurrence of previously undetected mutations in L3 (ST2 lineage) and L4 (ST3 lineage) ribosomal proteins and substitutions in the rpoB gene. The occurrence of LR-MRSE should be carefully monitored in order to prevent the spread of this difficult-to-treat pathogen and to preserve the efficacy of linezolid.

SVR-flaA typing of erythromycin- and ciprofloxacin-resistant Campylobacter jejuni strains isolated from poultry slaughterhouses in southern Brazil.

The emergence of fluoroquinolone and macrolide resistance in C. jejuni, a recognized zoonotic pathogen, has increased worldwide. This study aimed to investigate phenotypic resistance to ciprofloxacin and erythromycin, the molecular mechanisms involved, and the strain of C. jejuni isolated from broiler carcasses. Eighty C. jejuni isolates from broiler carcasses in southern Brazil were investigated for their susceptibility to ciprofloxacin and erythromycin at minimal inhibitory concentrations. Mismatch amplification mutation assay-polymerase chain reaction (MAMA-PCR) was performed to detect substitutions of Thr-86-Ile, A2074C, and A2075G of domain V in the 23S rRNA. The presence of ermB gene and CmeABC operon were investigated by PCR. DNA sequencing was used to detect substitutions in the L4 and L22 proteins of the erythromycin-resistant strains. The Short Variable Region (SVR) of flaA was used to type all the strains resistant to both antimicrobials. Ciprofloxacin and erythromycin resistance were detected in 81.25% and 30.00% of the strains, respectively, and minimal inhibitory concentration values ranged from ≤ 0.125 to 64µg/mL for ciprofloxacin and 0.5 to > 128µg/mL for erythromycin. The Thr-86-Ile mutation in gyrA was observed in 100% of the ciprofloxacin-resistant strains. Mutations in both the A2074C and A2075G positions of 23S rRNA were observed in 62.5% of the erythromycin-resistant strains, while 37.5% had only the mutation A2075G. None of the strains harbored CmeABC operon, and ermB was not detected. Using DNA sequencing, the amino acid substitution T177S was detected in L4, and substitutions I65V, A103V, and S109A were detected in L22. Twelve flaA-SVR alleles were identified among the strains, with the most common SVR-flaA allele, type 287, covering 31.03% of ciprofloxacin- and erythromycin-resistant isolates. The present study revealed a high incidence and high levels of resistance to ciprofloxacin and erythromycin, as well as broad molecular diversity in C. jejuni isolates from broiler carcasses.

Phenotypic and genotypic characterization of linezolid resistance and the effect of antibiotic combinations on methicillin-resistant Staphylococcus aureus clinical isolates

BackgroundMethicillin-Resistant Staphylococcus aureus (MRSA) causes life-threatening infections, with narrow therapeutic options including: vancomycin and linezolid. Accordingly, this study aimed to characterize phenotypically and genotypically, the most relevant means of linezolid resistance among some MRSA clinical isolates.MethodsA total of 159 methicillin-resistant clinical isolates were collected, of which 146 were indentified microscopically and biochemically as MRSA. Both biofilm formation and efflux pump activity were assessed for linezolid-resistant MRSA (LR-MRSA) using the microtiter plate and carbonyl cyanide 3-chlorophenylhydrazone (CCCP) methods, respectively. Linezolid resistance was further characterized by polymerase chain reaction (PCR) amplification and sequencing of domain V of 23 S rRNA; rplC; rplD;and rplV genes. Meanwhile, some resistance genes were investigated: cfr; cfr(B); optrA; msrA;mecA; and vanA genes. To combat LR-MRSA, the effect of combining linezolid with each of 6 different antimicrobials was investigated using the checkerboard assay.ResultsOut of the collected MRSA isolates (n = 146), 5.48% (n = 8) were LR-MRSA and 18.49% (n = 27) were vancomycin-resistant (VRSA). It is worth noting that all LR-MRSA isolates were also vancomycin-resistant. All LR-MRSA isolates were biofilm producers (r = 0.915, p = 0.001), while efflux pumps upregulation showed no significant contribution to development of resistance (t = 1.374, p = 0.212). Both mecA and vanA genes were detected in 92.45% (n = 147) and 6.92% (n = 11) of methicillin-resistant isolates, respectively. In LR-MRSA isolates, some 23 S rRNA domain V mutations were observed: A2338T and C2610G (in 5 isolates); T2504C and G2528C (in 2 isolates); and G2576T (in 1 isolate). Amino acids substitutions were detected: in L3 protein (rplC gene) of (3 isolates) and in L4 protein (rplD gene) of (4 isolates). In addition, cfr(B) gene was detected (in 3 isolates). In 5 isolates, synergism was recorded when linezolid was combined with chloramphenicol, erythromycin, or ciprofloxacin. Reversal of linezolid resistance was observed in some LR-MRSA isolates when linezolid was combined with gentamicin or vancomycin.ConclusionsLR-MRSA biofilm producers’ phenotypes evolved in the clinical settings in Egypt. Various antibiotic combinations with linezolid were evaluated in vitro and showed synergistic effects.

Characterization of Linezolid-Analogue L3-Resistance Mutation in Staphylococcus aureus

In a previous study, a linezolid analogue, called 10f, was synthesized. The 10f molecule has an antimicrobial activity comparable to that of the parental compound. In this study, we isolated a Staphylococcus aureus (S. aureus) strain resistant to 10f. After sequencing the 23S rRNA and the ribosomal proteins L3 (rplC) and L4 (rplD) genes, we found that the resistant phenotype was associated with a single mutation G359U in rplC bearing to the missense mutation G120V in the L3 protein. The identified mutation is far from the peptidyl transferase center, the oxazolidinone antibiotics binding site, thus suggesting that we identified a new and interesting example of a long-range effect in the ribosome structure.

Assessment of superiority of HSP70-targeting aptamer-functionalized drug-nanocarrier over non-targeted commercially available counterpart in HCC therapy: in vitro and in vivo investigations and molecular modeling

AimsThis research aims to compare the therapeutic potential of target-specific phosphorothioate backbone-modified aptamer L5 (TLS9a)-functionalized paclitaxel (PTX)-loaded nanocarrier (PTX-NPL5) that we formulated with that of non-targeted commercial formulation, protein albumin-bound nanoparticles of PTX, Abraxane® (CF) against hepatocellular carcinoma (HCC) through a myriad of preclinical investigations. Main methodsA variety of in vitro and in vivo assays have been executed to compare the therapeutic effects of the formulations under investigation, including the investigation of the degree of apoptosis induction and its mechanism, cell cycle analysis, the level of ROS production, and redox status, the morphological and histological characteristics of malignant livers, and in vivo imaging. The formulations were also compared concerning pharmacokinetic behaviors. Finally, in silico molecular docking has been performed to predict the possible interactions between aptamer and target(s). Key findingsPTX-NPL5 exhibited therapeutic superiority over CF in terms of inducing apoptosis, cell cycle arrest, endorsing oxidative stress to neoplastic cells, and reducing hepatic cancerous lesions. Unlike CF, PTX-NPL5 did not exhibit any significant toxicity in healthy hepatocytes, proving enough impetus regarding the distinctive superiority of PTX-NPL5 over CF. The pharmacokinetic analysis further supported superior penetration and retention of PTX-NPL5 in neoplastic hepatocytes compared to CF. A molecular modeling study proposed possible interaction between aptamer L5 and heat shock protein 70 (HSP70). SignificanceThe target-specificity of PTX-NPL5 towards neoplastic hepatocytes, probably achieved through HSP70 recognition, enhanced its therapeutic efficacy over CF, which may facilitate its real clinical deployment against HCC in the near future.

A Comprehensive Study on Antibiotic Resistance among Coagulase-Negative Staphylococci (CoNS) Strains Isolated from Ready-to-Eat Food Served in Bars and Restaurants.

The present study aimed to characterize and assess the diversity of CoNS strains as potential vectors for the spread of resistance to antimicrobial agents from RTE foods served in bars and restaurants. Eighty-five CoNS strains, obtained from 198 RTE food samples, were investigated. Sixty-seven CoNS isolates (78.8%) were resistant to at least one antibiotic tested, and 37 (43.5%) were multidrug resistant (MDR-CoNS). Moreover, CoNS strains contained genes conferring resistance to antibiotics critically important in medicine, i.e., β-lactams [mecA (29.4%); blaZ (84.7%)], aminoglycosides [aac(6')-Ie-aph(2″)-Ia (45.9%); aph(2″)-Ic (3.5%)], macrolides, lincosamides and streptogramin B-MLSB [msrA/B (68.2%); ermB (40%) and mphC (4.7%)], tetracyclines [tetK (31.8%); tetM (16.5%) and/or tetL (2.35%)]. We also found the fusB/C/D genes responsible for the acquired low-level fusidic acid resistance (17.6%) and streptogramin resistance determinant vgaA in 30.6% of isolates. In three linezolid resistant strains (2 S. epidermidis and 1 S. warneri), mutation was detected, as demonstrated by L101V and V188I changes in the L3 protein amino acid sequences. The high frequency in RTE food of MDR-CoNS including methicillin-resistant (MR-CoNS) strains constitutes a direct risk to public health as they increase the gene pool from which pathogenic bacteria can pick up resistance traits.

Transcriptome profile and its partly verification of human hepatocellular carcinoma cells exposed to Yuzhizi () seed extract.

To investigate the efficacy of Yuzhizi seed extract (FAQSE) on inhibiting the proliferation of hepatocellular carcinoma (HCC) cells in vitro and to explore the anti-HCC action mechanism of FAQSE. Human HCC HepG2 and Huh7 cells were used to investigate the anti-HCC effect of FAQSE. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) method was used to measure cell viability. Affymetrix microarray was adopted to detect the expression of transcriptome. The differentially expressed genes (DEGs) of each cell line were identified. For co-DEGs of both cell lines, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were enriched using the Database for Annotation, Visualization and Integrated Discovery (DAVID), and the network analysis of protein-protein interaction (PPI) was mapped using the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape software. Some important genes in the PPI network of co-DEGs were selected to verify by quantitative real-time reverse transcription-polymerase chain reaction, Western blot and enzyme-linked immunosorbent assay. FAQSE decreased the viability of HepG2 and Huh7 cells. There were 211 co-upregulated and 86 co-downregualted genes in both cell lines after FAQSE treatment. The enriched GO terms of co-upregulated DEGs were primarily involved cell-cell adhesion, viral process, transcription initiation from RNA polymerase II promoter, positive regulation of transcription from RNA polymerase II promoter and actin cytoskeleton organization. The GO terms of co-downregulated DEGs were mainly enriched in the processes of SRP-dependent cotranslational protein targeting to membrane, viral transcription, nuclear-transcribed mRNA catabolic process, nonsense-mediated decay, translational initiation and rRNA processing. Main KEGG pathways of co-upregulated DEGs were endocytosis, glutathione metabolism, protein processing in endoplasmic reticulum, synaptic vesicle cycle and lysosome. The major KEGG pathways of co-downregulated DEGs were ribosome, biosynthesis of amino acids, arginine and proline metabolism, systemic lupus erythematosus and complement and coagulation cascades. The top 10 co-DEGs with high hub nodes in STRING analysis were ribosomal protein S27a, transferrin, ribosomal protein S20, ribosomal protein L9, protein phosphatase 2 regulatory subunit B alpha, transthyretin, thioredoxin reductase 1, ribosomal protein L3, ribophorin I and ribosomal protein L24. Alpha-fetoprotein (AFP) was also co-downregulated and contained in the PPI network. The mRNA and protein expression of most verified genes was consistent with the results of co-DEGs analysis. And the AFP level was significantly reduced after FAQSE treatment. A series of genes and pathways of HepG2 and Huh7 cells were changed after FAQSE treatment, which might be the targets of FAQSE against HCC and worthy of further study. AFP might be important one of them.

Mechanisms of linezolid resistance in Staphylococcus capitis with the novel mutation C2128T in the 23S rRNA gene in China

PurposeThe objective of this study was to investigate the molecular characteristics and potential resistance mechanisms of linezolid-resistant (LZR) Staphylococcus capitis isolates from a tertiary hospital in China.MethodsS. capitis isolates were obtained from clinical patient specimens; three of the isolates came from blood cultures and one from the hydrothorax. The agar dilution and E-test methods were used to identify antibiotic resistance. The chloramphenicol-florfenicol resistance (cfr) gene carrier status of the strains was determined by PCR. Whole-genome sequencing (WGS) was used to identify point mutations and L3, L4, and L22 mutations and to study the genetic environment of the cfr gene and the relationships between strains.ResultsThe 4 isolates obtained in this study were all linezolid-resistant Staphylococcus strains. A similar of susceptibility profile pattern was observed in all four S. capitis strains, each of which exhibited a multidrug-resistant phenotype. A potentially novel mutation, C2128T, was identified, and the cfr genes of S. capitis strains were all positive. Additionally, the same mutations (C2128T and G2600T) were identified in all 23S rRNA sequences of the isolates, whereas mutations were lacking in the L3, L4, and L22 ribosomal proteins. The genetic environments surrounding cfr were identical in all four isolates. A schematic diagram of the phylogenetic tree showed that they were closely related to AYP1020, CR01, and TW2795, and a total of seven drug resistance genes were identified in these strains.ConclusionsThe study indicated that the resistance of the Staphylococcus capitis strains to linezolid was caused by multiple mechanisms, and a potential novel mutation, C2128T, that may have an impact on bacterial resistance was identified.

Magnetic Resonance Imaging and Serum AFP-L3 and GP-73 in the Diagnosis of Primary Liver Cancer.

Objective To investigate the combined application value of magnetic resonance imaging (MRI) combined with serum alpha-fetoprotein (AFP)-L3 and Golgi protein (GP)-73 in the diagnosis of primary liver cancer. Methods The data of 200 patients with suspected liver cancer admitted to our hospital from February 2020 to February 2021 were retrospectively analyzed, and they were randomly divided into an experimental group and a control group, with 100 cases in each group. The experimental group received a combined detection of MRI with serum AFP-L3 and GP-73, and the control group adopted traditional diagnostic methods (spiral computed tomography and serum AFP). The diagnostic yields of the two groups were compared. Surgical resection was performed after the diagnosis of primary liver cancer, and the correlation between the efficacy and combined detection of MRI with serum AFP-L3 and GP-73 levels was analyzed. Results The two groups presented comparable general information (P >0.05). The surgical results showed 160 cases of primary liver cancer, including 75 cases in the experimental group and 85 cases in the control group, and 40 cases of benign liver lesions. The diagnostic accuracy of the experimental group (73/75, 95%) was significantly higher than that of the control group (76/85, 86%) (P < 0.05). The serum levels of AFP-L3, GP-73, and AFP in patients with primary liver cancer were remarkably decreased after surgery (P < 0.001). The preoperative and postoperative AFP-L3, GP-73, and AFP levels of patients with primary liver cancer were significantly higher than those of patients with benign liver lesions. The AUC (95% CI) for the combined detection of MRI and serum AFP-L3 and GP-73 levels in patients with surgically confirmed primary liver cancer was 0.747 (0.619-0.874). Conclusion MRI combined with serum AFP-L3 and GP-73 presents favorable diagnostic efficiency in the diagnosis of primary liver cancer, which is worthy of clinical application.

Interaction Analysis of Adenovirus L5 Protein With Pancreatic Cancer Cell Surface Receptor to Analyze Its Affinity for Oncolytic Virus Therapy.

This study seeks to investigate the interaction profile of the L5 protein of oncolytic adenovirus with the overexpressed surface receptors of pancreatic cancer. This is an important area of research because pancreatic cancer is one of the most fatal malignancies with a very low patient survival rate. Multiple therapies to date to improve the survival rate are reported; however, they show a comparatively low success rate. Among them, oncolytic virus therapy is a type of immunotherapy that is currently under deliberation by researchers for multiple cancer types in various clinical trials. Talimogene laherparepvec (T-VEC) is the first oncolytic virus approved by the US Food and Drug Administration (FDA) for melanoma. The oncolytic virus not only kills cancer cells but also activates the anticancer immune response. Therefore, it is preferred over others to deal with aggressive pancreatic cancer. The efficacy of therapy primarily depends on how effectively the oncolytic virus enters and infects the cancer cell. Cell surface receptors and their interactions with virus coat proteins are a crucial step for oncolytic virus entry and a pivotal determinant. The L5 proteins of the virus coat are the first to interact with host cell surface receptors. Therefore, the objective of this study is to analyze the interaction profile of the L5 protein of oncolytic adenovirus with overexpressed surface receptors of pancreatic cancer. The L5 proteins of three adenovirus serotypes HAdV2, HAdV5, and HAdV3 were utilized in this study. Overexpressed pancreatic cancer receptors include SLC2A1, MET, IL1RAP, NPR3, GABRP, SLC6A6, and TMPRSS4. The protein structures of viral and cancer cell protein were docked using the High Ambiguity Driven protein–protein DOCKing (HADDOCK) server. The binding affinity and interaction profile of viral proteins against all the receptors were analyzed. Results suggest that the HAdV3 L5 protein shows better interaction as compared to HAdV2 and HAdV5 by elucidating high binding affinity with 4 receptors (NPR3, GABRP, SLC6A6, and TMPRSS4). The current study proposed that HAdV5 or HAdV2 virus pseudotyped with the L5 protein of HAdV3 can be able to effectively infect pancreatic cancer cells. Moreover, the current study surmises that the affinity maturation of HAdV3 L5 can enhance virus attachment with all the receptors of cancer cells.

Loss of RPS27a expression regulates the cell cycle, apoptosis, and proliferation via the RPL11-MDM2-p53 pathway in lung adenocarcinoma cells

BackgroundDepletion of certain ribosomal proteins induces p53 activation, which is mediated mainly by ribosomal protein L5 (RPL5) and/or ribosomal protein L11 (RPL11). Therefore, RPL5 and RPL11 may link RPs and p53 activation. Thus, this study aimed to explore whether RPs interact with RPL11 and regulate p53 activation in lung adenocarcinoma (LUAD) cells.MethodsThe endogenous RPL11-binding proteins in A549 cells were pulled down through immunoprecipitation and identified with a proteomics approach. Docking analysis and GST-fusion protein assays were used to analyze the interaction of ribosomal protein S27a (RPS27a) and RPL11. Co-immunoprecipitation and in vitro ubiquitination assays were used to detect the effects of knockdown of RPS27a on the interaction between RPS27a and RPL11, and on p53 accumulation. Cell cycle, apoptosis, cell invasion and migration, cell viability and colony-formation assays were performed in the presence of knockdown of RPS27a. The RPS27a mRNA expression in LUAD was analyzed on the basis of the TCGA dataset, and RPS27a expression was detected through immunohistochemistry in LUAD samples. Finally, RPS27a and p53 expression was analyzed through immunohistochemistry in A549 cell xenografts with knockdown of RPS27a.ResultsRPS27a was identified as a novel RPL11 binding protein. GST pull-down assays revealed that RPS27a directly bound RPL11. Knockdown of RPS27a weakened the interaction between RPS27a and RPL11, but enhanced the binding of RPL11 and murine double minute 2 (MDM2), thereby inhibiting the ubiquitination and degradation of p53 by MDM2. Knockdown of RPS27a stabilized p53 in an RPL11-dependent manner and induced cell viability inhibition, cell cycle arrest and apoptosis in a p53-dependent manner in A549 cells. The expression of RPS27a was upregulated in LUAD and correlated with LUAD progression and poorer prognosis. Overexpression of RPS27a correlated with upregulation of p53, MDM2 and RPL11 in LUAD clinical specimens. Knockdown of RPS27a increased p53 activation, thus, suppressing the formation of A549 cell xenografts in nude mice.ConclusionsRPS27a interacts with RPL11, and RPS27a knockdown enhanced the binding of RPL11 and MDM2, thereby inhibiting MDM2-mediated p53 ubiquitination and degradation; in addition, RPS27a as important roles in LUAD progression and prognosis, and may be a therapeutic target for patients with LUAD.Graphical

Emergence of optrA-Mediated Linezolid Resistance in Enterococcus faecium: A Molecular Investigation in a Tertiary Hospital of Southwest China from 2014-2018.

PurposeTo investigate the potential mechanism and molecular characteristics of linezolid-non-sensitive Enterococcus faecium from a tertiary hospital in southwest China and characterize the relevant plasmids.Patients and MethodsLinezolid-non-sensitive Enterococcus faecium (LNSEFM) isolates collected from January 2014 to December 2018 were screened for resistant genes 23s rRNA, rplC, rplD, rplV, optrA, cfr, poxtA, by PCR. Molecular epidemiological analysis was performed by multilocus sequence typing (MLST). The optrA-and-poxtA co-harboring strain EFM_7150 was subjected to the whole genome sequencing (WGS) by Illumina HiSeq and Oxford Nanopore MinION.ResultsA total of 15 LNSEFM with linezolid MICs ranging from 4 to 16 mg/L were identified. About 66.7% (10/15) of isolates were linezolid-resistant. About 46.7% (7/15) of strains were positive for optrA. Two types of optrA variants (P and EYDNDM) were identified. About 13.3% (2/15) of isolates had poxtA. 1 harbored a L22 protein alteration (Ser77Thr). One isolate coharbored optrA (EYDNDM variant) and poxtA. There was no mutation in the gene that encoded the ribosomal protein L3/L4 or the domain V of 23S rRNA. No cfr gene was detected. Based on WGS data, optrA was associated with Tn558 inserted to radC gene and poxtA was flanked by IS1216E.ConclusionOptrA is primary mechanism in linezolid-resistant Enterococcus faecium. This is the first report ofoptrA variants P and EYDNDM identified in Enterococcus faecium and optrA-and-poxtA co-harboring Enterococcus faecium clinically in southwest China. Besides, Tn558 and IS1216Es may play an important role in the dissemination of optrA and poxtA, respectively. The findings revealed the potential threat to nosocomial infection by optrA and coexistence of optrA and poxtA in Enterococcus faecium. Thus, clinical surveillance of linezolid-resistant Enterococcus is urgently needed.

Resistance to 16-Membered Macrolides, Tiamulin and Lincomycin in a Swine Isolate of Acholeplasma laidlawii.

Acholeplasma (A.) laidlawii is an opportunistic pathogen with the ability to disseminate resistance determinants to antibiotics; however, its resistance to macrolides has been less studied. The aim of the present study was to characterize the mechanisms responsible for the resistance to macrolides, tiamulin and lincomycin found in a strain of A. laidlawii isolated from a pig with pneumonia. MICs of erythromycin, 15- and 16-membered macrolides, tiamulin and lincomycin were determined by microdilution method with and without reserpine, an inhibitor of ABC efflux pumps and regions of the genome were sequenced. Reserpine only decreased lincomycin MIC but it did not change the MICs of macrolides and tiamulin. The analysis of the DNA sequence of 23S rRNA showed nucleotide substitutions at eight different positions, although none of them were at positions previously related to macrolide resistance. Five mutations were found in the L22 protein, one of them at the stop codon. In addition, two mutations were found in the amino acid sequence of L4. The combination of multiple mutations in the ribosomal proteins L22 and L4 together with substitutions in 23S rRNA DNA sequence was associated with the resistance to macrolides, the pleuromutilin and lincomycin in the studied A. laidlawii strain.

Increased Calcitonin Gene-Related Peptide Expression in DRG and Nerve Fibers Proliferation Caused by Nonunion Fracture in Rats.

PurposeNonunion bone fracture can be a cause of persistent pain, but the pathophysiology remains largely unknown. The objective of this study was to identify how nonunion affect persistent pain after fracture. Specifically, we evaluated the association of neuropeptide change in dorsal root ganglia (DRG) and nerve proliferation at fracture sites with pain.MethodsRat union and nonunion fracture models were created. A piece of latex glove was placed at the fracture site to create a nonunion model. At 6 weeks after surgery, bone healing was assessed using radiography. In addition, the presence of calcitonin gene-related peptide-immunoreactive (CGRP-IR) DRG at the level of L3 and anti-growth associated protein 43-immunoreactive (GAP43-IR) nerve fibers in the scar tissue between the bone fragments were evaluated. Pain-related behavior was assessed using forced treadmill running.ResultsIn radiological images at 6 weeks after surgery, callus formation was formed continuously between bone fragments in the union models. On the one hand, a clear gap was detected between fragments in nonunion models. The percentage of CGRP-IR DRG cells and the density of GAP43-IR nerve fibers in the scar tissue between the bone fragments in nonunion models was significantly higher than that in union models (p < 0.05). An increase in inflammatory cell infiltrate was observed in scar tissues in the nonunion models. During forced treadmill running, rats in the union model could run significantly longer than those in the nonunion models.ConclusionIncreased CGRP expression in DRG cells and abnormal nerve proliferation secondary to prolonged inflammation could lead to persistent pain after bone fracture. In clinical practice, early achievement of bone union may minimize the development of persistent pain after fractures.

The RING-type protein BOI negatively regulates the protein level of a CC-NBS-LRR in Arabidopsis

Nucleotide-binding site and leucine-rich repeat receptors (NLRs) play pivotal roles in plant immunity. The regulation of NLR stability is essential to ensure effective immunity, whereas the exact mechanism is largely unclear. The Arabidopsis CC-NBS-LRR protein L5 (At1g12290) can induce cell death in Nicotiana benthamiana, but not in Arabidopsis thaliana. We screened the interactors of L5 by yeast two-hybrid, and found that the BOI can interact with the CC domain of L5. Transiently expressed BOI reduced the protein level of L5, and suppressed the auoactivity of L5 in N. benthamiana. BOI can interact and ubiquitinate L5 in vitro, and mediate the proteasomal degradation of L5 in N. benthamiana and Arabidopsis. The Lys425 in the NBS domain of L5 is the critical unbiquitin site for the degradation. In conclusion, our results reveal a mechanism for the control of the stability of L5 protein and for the suppressed of L5-triggered cell death by a RING-type E3 ligase through the ubiquitin proteasome system.

The important role of RPS14, RPL5 and MDM2 in TP53-associated ribosome stress in mycophenolic acid-induced microtia

ObjectiveMycophenolate embryopathy (ME) is a congenital malformation induced by mycophenolic acid (MA). Microtia is the most common ME phenotype. This study aimed to identify the key genes in the pathological process of microtia caused by mycophenolate mofetil (MM) through bioinformatics methods, to explore the potential pathogenesis, and to provide a direction for future genetic research on aetiology. MethodsGenes related to MM and microtia were obtained from the GeneCards database for bioinformatics. Metacore was used to identify and visualize the upstream and downstream gene relationships in the protein-protein interaction (PPI) results of these genes. The clusterProfiler R software package was used to simulate and visualize the enrichment results based on data from Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. ResultsFifty-nine genes were associated with microtia and MM/MA. The hub genes with the most significant effects on MM/MA-induced microtia pathogenesis included tumour protein P53 (p53), MDM2 proto-oncogene (MDM2), ribosomal protein L5 (RPL5) and ribosomal protein S14 (RBS14). The GO term with the most enriched genes was peptidyl-tyrosine phosphorylation. For the KEGG terms, there was significant enrichment regarding the haematopoietic cell lineage, apoptosis, p53 signalling, proteasome and necroptosis. ConclusionsWe propose that an axis composed of MA, microtia, TP53 and related genes is involved in ME pathogenesis. The important role of TP53-associated ribosome stress in ME pathogenesis is consistent with our previous findings from MA-induced cleft lip and palate. Deregulation of genes protective against TP53 overexpression, such as MDM2, could be a strategy for constructing a microtia animal model.

Chilling injury mechanism of hardy kiwifruit (Actinidia arguta) was revealed by proteome of label-free techniques.

Refrigeration is an important method to extend shelf life of hardy kiwifruit. However, the inappropriate storage temperature can lead to chilling injury in the fruit. We found that firmness, total soluble solids, and total polyphenolic content of the fruit exposed to 0℃ environment were apparently lower, and titratable acidity content, browning rate, weight loss rate, electrolyte leakage, proline content, and malondialdehyde content were higher obviously than 4℃. A total of 244 differentially expressed proteins were found result from differential temperatures, among which 113 were up-regulated and 131 were down-regulated. Subcellular localization results presented that the differentially expressed proteins which were affected by low temperature were located in cytoplasmic, chloroplast, nuclear, mitochondrial, plasma membrane, and extracellular. Kyoto Encyclopedia of Genes and Genomes analysis showed that the differentially expressed proteins were mainly participated in synthesis of citrate cycle, oxidative phosphorylation, fatty acid biosynthesis, and starch and sucrose metabolism. Protein-protein interaction results revealed that central proteins interaction points respectively are 30S ribosomal proteins, 30S ribosomal protein S7, chloroplastic, cell division cycle 5-like protein, 50S ribosomal protein, ribosomal protein, ribosomal protein L6 protein, and SRP54 subunit protein. The quality deviations of all identified peptides were mainly distributed within 10ppm, and MS2 has an ideal andromeda score, with more than 87.82% peptide scores above 60 points, and the median peptide score of 99.28 points. Therefore, the results of this study provide important information for new gene revelation and gene interaction relationship in hardy kiwifruit of chilling injury. PRACTICAL APPLICATIONS: Inhibition of cold damage in hardy kiwifruit under low temperature is very important work for the development of its storage industry. However, many qualities of fruit will deteriorate after long-term cold storage and those biological activities of the fruits are regulated by proteins. It is, therefore, of great significance to reveal the key proteins caused cold damage in hardy kiwifruit. Moreover, the study results could provide a scientific information for the quality improvement and genetic modification of hardy kiwifruit.

Multiplexing surface anchored functionalized iron carbide nanoparticle: A low molecular weight proteome responsive nano-tracer

Harvesting the low molecular weight (LMW) proteins from the cellular exudates is a big challenge for early disease detection. Here, we introduce a unique probe composed of surface-functionalized Fe2C NPs with different functional groups to harvest, identify and profile differentially expressed biomarker proteins. Three different functionalization of Fe2C NPs with Fe2C@NH2, Fe2C@COOH and Fe2C@PEG enabled to harvest 119 differentially expressed proteins from HeLa cell exudates. Among these proteins, 57 were LMW which 82.46 % were up-regulated and 17.54 % were down-regulated. The Fe2C@NH2 were able to separate 60S ribosomal proteins L7a, and L11, and leucine-rich repeat-containing protein 59. These proteins play a vital role in the maturation of large subunit ribosomal ribonucleic acid, mRNA splicing via spliceosome and cancer cell inhibitor, respectively. While, Fe2C@COOH identifies the 60S ribosomal protein types L7, 40S ribosomal protein S11, and 60S ribosomal protein L24. These proteins were important for large ribosomal subunit biogenesis, translational initiation, and assembly of large subunit precursor of pre-ribosome. Finally, the Fe2C@PEG extracted 40S ribosomal protein S2, splicing factor, arginine/serine-rich and 40S ribosomal protein S4, X isoform which were responsible for nonsense-mediated decay, oligodendrocyte differentiation and multicellular organism development. Thus, these results help us in defining oncogenic biomarkers for early disease detection.

Pressure-Temperature Landscape of the Unfolded State of Clt9-I98A Protein

The nature of the pressure-unfolded state of a protein is still under debate. Since high pressure favours states with lower molar volume, the pressure-unfolded state is often thought to be more compact than a random coil. However, differences between effect of pressure and other unfolding methods might often reflect the fact that pressure acts locally on the protein structure and hence differentially destabilizes different domains of a protein. The unfolded state of I98A mutant of the C-terminal domain of L9 protein has been studied by pH, urea denaturation and also cold temperature, since the protein undergoes cold denaturation above 0°C.