Two-component System Research Articles

Regulation of magnesium ion transport in Escherichia coli: insights into the role of the 5’ upstream region in corA expression

ABSTRACT In Escherichia coli, transport of magnesium ions across the cellular membrane relies on MgtA and CorA transporters. While the expression of mgtA is controlled by the two-component system PhoQ/PhoP and 5’ upstream region elements, corA expression is considered to be constitutive and not to depend on cellular factors. Importantly, the 5’ upstream region of corA is predicted to fold into structures highly similar to the magnesium-sensing mgtA 5‘ upstream region. Here using biochemical and genetic assays, we show that the intracellular concentration of magnesium ions affects corA expression. Similarly to mgtA, we find that the effect of magnesium ions on corA expression is mediated by the 5’ upstream region. We demonstrate that the RNA structure is important for regulation and that the Rho transcription factor is involved in the modulation of transcription termination. Consistent with previous studies, we find that translation of corL, a short ORF located within the 5’ upstream region, is important for corA regulation. Our data indicate that the efficiency of corL translation is inversely proportional to corA expression, similar to what has been described for mgtA and corA in Salmonella enterica. Using a novel assay to control the import of magnesium ions, we show that while the expression of mgtA is regulated by both extra- and intracellular magnesium ions, corA is regulated by variations in intracellular magnesium ions. Our results support a model in which the expression of corA is regulated by the 5’ upstream region that senses variations of intracellular magnesium ions.

Epinephrine and norepinephrine regulate the expression of virulence factors in Gallibacterium anatis

Gallibacterium anatis is a member of the Pasteurellaceae family and is an opportunistic pathogen that causes gallibacteriosis in chickens. Stress plays a relevant role in promoting the development of pathogenicity in G. anatis. Epinephrine (E) and norepinephrine (NE) are relevant to stress; however, their effects on G. anatis have not been elucidated. In this work, we evaluated the effects of E and NE on the growth, biofilm formation, expression of adhesins, and proteases of two G. anatis strains, namely, the hemolytic 12656-12 and the nonhemolytic F149T biovars. E (10μM/mL) and NE (30 and 50μM/mL) increased the growth of G. anatis 12656-12 by 20% and 25%, respectively. E did not affect the growth of F149T, whereas 40μM/mL NE decreased bacterial growth by 25%. E and NE at a dose of 30-50μM/mL upregulated five fibrinogen adhesins in the 12565-12 strain, whereas no effect was observed in the F149T strain. NE increased proteolytic activity in both strains, whereas E diminished proteolytic activity in the 12656-12 strain. E and NE reduced biofilm formation (30%) and increased Congo red binding (15%) in both strains. QseBC is the E and NE two-component detection system most common in bacteria. The qseC gene, which is the E and NE receptor in bacteria, was identified in the genomic DNA of the 12565-12 and F149TG. anatis strains via PCR amplification. Our results suggest that QseC can detect host changes in E and NE concentrations and that catecholamines can modulate the expression of several virulence factors in G. anatis.

Pulses in singularly perturbed reaction-diffusion systems with slowly mixed nonlinearity.

This article is concerned with the existence and spectral stability of pulses in singularly perturbed two-component reaction-diffusion systems with slowly mixed nonlinearity. In this paper, the slow nonlinearity is referred to be "mixed" in the sense that it is generated by a trigonometric function multiplied by a power function. We demonstrate via geometric singular perturbation theory that this model can support both the single-pulse and the double-hump solutions. The presence of the slowly mixed nonlinearity complicates the stability analysis on pulses, since the conditions that govern their stability can no longer be explicitly computed. We remove this difficulty by introducing the hypergeometric functions followed by a comparison theorem. By doing so, the "slow-fast" eigenvalues can be determined via the nonlocal eigenvalue problem method. We prove that the double-hump solution is always unstable, while the single-pulse solution can be stable under certain parameter conditions.

Methylisothiazolinone modulates community assembly and improves syntrophic cooperation via adaptive evolution during sludge anaerobic digestion

Various antimicrobials could pose multifaced threats to anaerobic digestion (AD) of waste-activated sludge (WAS), yet it is still unclear how antimicrobials would affect the metabolic activity and assembly process of anaerobic microbiome. In this study, a typical antimicrobial, methylisothiazolinone (MIT), was introduced in AD and induced an initial lag effect on methane production that was eventually recovered. Although MIT disintegrated WAS to promote the release of bioavailable substrates from extracellular polymeric substances (EPS), it also caused adverse stress to the microbiome. The initial microbial metabolic activities and syntrophic relationships associated with methane generation were distinctly inhibited. Because the self-adaptive systems of two-component systems (e.g., ddpF, and ddpD) and quorum sensing (e.g., cheR, and cydB) were activated to restore the syntrophic interaction among functional anaerobes, metabolic activities were gradually recovered for methane generation. Ultimately, the methane-generation species (e.g., Methanobacterium, and Methanomassiliicoccus) were driven as core species by deterministic processes, while non-functional species (e.g., Nitrospirota) were marginalized by stochastic processes under MIT stress. Overall, this finding indicated the intrinsic drive of evolutionary adaptation, unraveled the community assembly process at phylogenetic level under antimicrobial stress, and gave direction on the assessment and mitigation of external contaminant-related ecological risks in WAS treatment.

Translation profiling of stress-induced small proteins reveals a novel link among signaling systems.

Signaling networks allow adaptation to stressful environments by activating genes that counteract stressors. Small proteins (≤ 50 amino acids long) are a rising class of stress response regulators. Escherichia coli encodes over 150 small proteins, most of which lack phenotypes and their biological roles remain elusive. Using magnesium limitation as a stressor, we identify stress-induced small proteins using ribosome profiling, RNA sequencing, and transcriptional reporter assays. We uncover 17 small proteins with increased translation initiation, several of them transcriptionally upregulated by the PhoQ-PhoP two-component signaling system, crucial for magnesium homeostasis. Next, we describe small protein-specific deletion and overexpression phenotypes, underscoring their physiological significance in low magnesium stress. Most remarkably, we elucidate an unusual connection via a small membrane protein YoaI, between major signaling networks - PhoR-PhoB and EnvZ-OmpR in E. coli, advancing our understanding of small protein regulators in cellular signaling.

Rapid Synthesis of anti-1,3-Diamino-4-phenylbutan-2-ol Building Blocks via a Three-Component Oxyhomologation and a Two-Component Reducing System.

N1-substituted derivatives of anti-(2R,3S)-1,3-diamino-4-phenylbutan-2-ol are important building blocks for the synthesis of therapeutically important molecules. We describe a simple protocol that allows transformation of N,N-dibenzyl-L-phenylalaninal into such compounds in only two steps. The first step is a fully stereoselective three-component MAC (Masked Acyl Cyanide) oxyhomologation reaction implicating different amines to give a panel of ten N,N-dibenzyl-O-tert-butyldimethylsilyl-protected anti-(2S,3S)-allophenylnorstatin amides. The second step is a carbonyl-activated hydride deprotection/reduction protocol using trimethylsilyl chloride and lithium aluminium hydride; the one-pot two-component system is more efficient than the alternative approach of isolating the deprotected amide intermediate before reduction.

Development of a two component system based biosensor with high sensitivity for the detection of copper ions

Recent advancements in bacterial two-component systems (TCS) have spurred research into TCS-based biosensors, notably for their signal amplification and broad input responsiveness. The CusRS system in Escherichia coli (E. coli), comprising cusS and cusR genes, is a copper-sensing module in E. coli. However, due to insufficient sensing performance, CusRS-based biosensors often cannot meet practical requirements. To address this issue, we made improvements and innovation from several aspects. CusR and CusS expression were adjusted to enhance the Cu(II) biosensor’s performance. A copy-number inducible plasmid was used for signal amplification, while removing copper detox genes cueO and cusCFBA improved sensitivity and lowered detection limits. Ultimately, in the optimized biosensor of Cu26, the fold-change (I/I0) increased from 1.5-fold to 18-fold at 1 μM, rising to 100-fold after optimizing the cell culture procedure. The biosensor’s high fluorescence enabled rapid, instrument-free detection and an improved analysis strategy reduced the detection limit to 0.01 μM, surpassing traditional methods.

It takes two to tango: Preserving daptomycin efficacy against daptomycin-resistant MRSA using daptomycin-phage co-therapy.

Multidrug-resistant Staphylococcus aureus is a threat to the health care system, especially cross-resistance between daptomycin (DAP) and glycopeptides through various mutations such as mprF (which is involved in the modification of membrane phospholipids in some bacteria) and yycG (part of a two-component regulatory system in bacteria that is important for regulating cell wall biosynthesis and other cellular processes) has been reported previously. Our current study shows adjunctive treatment with phage in DAP-resistant strains will lead to synergistic activity and larger phage plaque sizes, translating to elevated lytic performance. The addition of bacteriophage to standard-of-care antibiotic therapies for multidrug-resistant S. aureus infections has the potential to hinder, and possibly revert, resistance to antibiotics. Applying this strategy can potentially lead to the preservation of the current antibiotics. Verification of this salutary outcome in relevant ex vivo and in vivo models of endovascular infections is required to validate translatability.

Effects of different carbapenemase and siderophore production on cefiderocol susceptibility in Klebsiella pneumoniae.

The resistance mechanism of Gram-negative bacteria to the siderophore antibiotic cefiderocol is primarily attributed to carbapenemase and siderophore uptake pathways; however, specific factors and their relationships remain to be fully elucidated. Here, we constructed cefiderocol-resistant Klebsiella pneumoniae (CRKP) strains carrying different carbapenemases and knocked out siderophore genes to investigate the roles of various carbapenemases and siderophores in the development of cefiderocol resistance. Antimicrobial susceptibility testing revealed that both blaNDM and blaKPC significantly increased the minimum inhibitory concentration (MIC) of Klebsiella pneumoniae (KP) to cefiderocol, while blaOXA-48 showed a modest increase. Notably, KP expressing NDM exhibited a higher cefiderocol MIC compared to KP expressing KPC, although expression of NDM alone did not induce cefiderocol resistance. Laboratory evolutionary experiments demonstrated that combining pNDM with mutations in the siderophore uptake receptor gene cirA and pKPC with a mutation in the two-component system gene envZ led to KP reaching a high level of cefiderocol resistance. Although combining pOXA with mutations in the two-component system gene baeS did not induce cefiderocol resistance, it significantly reduced susceptibility. Moreover, siderophores could influence the development of cefiderocol resistance. Strains deficient in enterobactin exhibited increased susceptibility to cefiderocol, while deficiencies in yersiniabactin and salmochelin showed no significant alterations. In conclusion, carbapenemase gene expression facilitates cefiderocol resistance, but its presence alone is insufficient. Cefiderocol resistance in CRKP typically involves abnormal expression of certain genes and other factors, such as mutations in siderophore uptake receptor genes and two-component system genes. The enterobactin siderophore synthesis gene entB may also contribute to resistance.

Genome-wide identification and expression analysis of two-component system genes in switchgrass (Panicum virgatum L.)

The two-component system (TCS) consists of histidine kinase (HK), histidine phosphate transfer protein (HP), and response regulatory factor (RR). It is one of the most crucial components of signal transduction in plants, playing a significant role in regulating plant growth, development, and responses to various abiotic stresses. Although TCS genes have been extensively identified in a variety of plants, the genome-wide recognition and examination of TCS in switchgrass remain unreported. Accordingly, this study identified a total of 87 TCS members in the genome of switchgrass, comprising 20 HK(L)s, 10 HPs, and 57 RRs. Detailed analyses were also conducted on their gene structures, conserved domains, and phylogenetic relationships. Moreover, this study analysed the gene expression profiles across diverse organs and investigated their response patterns to adverse environmental stresses. Results revealed that 87 TCS genes were distributed across 18 chromosomes, with uneven distribution. Expansion of these genes in switchgrass was achieved through both fragment and tandem duplication. PvTCS members are relatively conservative in the evolutionary process, but the gene structure varies significantly. Various cis-acting elements, varying in types and amounts, are present in the promoter region of PvTCSs, all related to plant growth, development, and abiotic stress, due to the TCS gene structure. Protein-protein interaction and microRNA prediction suggest complex interactions and transcriptional regulation among TCS members. Additionally, most TCS members are expressed in roots and stems, with some genes showing organ-specific expression at different stages of leaf and inflorescence development. Under conditions of abiotic stress such as drought, low temperature, high temperature, and salt stress, as well as exogenous abscisic acid (ABA), the expression of most TCS genes is either stimulated or inhibited. Our systematic analysis could offer insight into the characterization of the TCS genes, and further the growth of functional studies in switchgrass.

Constitutive activation of two-component systems reveals regulatory network interactions in Streptococcus agalactiae

Bacterial two-component systems (TCSs) are signaling modules that control physiology, adaptation, and host interactions. A typical TCS consists of a histidine kinase (HK) that activates a response regulator via phosphorylation in response to environmental signals. Here, we systematically test the effect of inactivating the conserved phosphatase activity of HKs to activate TCS signaling pathways. Transcriptome analyses of 14 HK mutants in Streptococcus agalactiae, the leading cause of neonatal meningitis, validate the conserved HK phosphatase mechanism and its role in the inhibition of TCS activity in vivo. Constitutive TCS activation, independent of environmental signals, enables high-resolution mapping of the regulons for several TCSs (e.g., SaeRS, BceRS, VncRS, DltRS, HK11030, HK02290) and reveals the functional diversity of TCS signaling pathways, ranging from highly specialized to interconnected global regulatory networks. Targeted analysis shows that the SaeRS-regulated PbsP adhesin acts as a signaling molecule to activate CovRS signaling, thereby linking the major regulators of host-pathogen interactions. Furthermore, constitutive BceRS activation reveals drug-independent activity, suggesting a role in cell envelope homeostasis beyond antimicrobial resistance. This study highlights the versatility of constitutive TCS activation, via phosphatase-deficient HKs, to uncover regulatory networks and biological processes.

On plutonium-241 and americium in the two-component nuclear energy system

The paper deals with the influence of the strategy for using separated plutonium from spent fuel of thermal and fast reactors, as well as homogeneous burning of americium in the BN reactor core on the balance of americium in the Russian nuclear fuel cycle throughout the 21st century. The assessment is carried out with the use of mathematical modeling of nuclear materials movement including nuclide transformations throughout the nuclear energy system based on the CYCLE code. Scenario modeling of the americium and Pu-241 accumulation was carried out in Russia’s two-component nuclear energy system model with thermal (VVER) and fast (BN) reactors. In so doing, spent nuclear fuel (SNF) reprocessing was simulated in 2 options: as priority reprocessing of SNF of VVER reactors (1) or SNF of BN reactors (2). In addition to americium accumulation in the system without burning, the accumulation of this actinide was studied taking into account its homogeneous burning in the MOX-fuel of fast reactors at the level of its equilibrium content of ~1%. It has been shown that the priority reprocessing of VVER spent fuel makes it possible to reduce the americium accumulation by the end of the century by ~8 tons, and the effect is achieved by using freshly separated plutonium with short-term cooling, thus, by priority the americium source is eliminated, without directly handling it. Homogeneous addition of americium to the fuel of fast reactors of the BN-1200 type at a level of ~1% makes it possible to stop accumulation of americium in a two-component energy system by 2070, stabilizing it at a level of ~40 tons in the scenario with priority reprocessing of VVER SNF and ~50 tons in the scenario with priority reprocessing of BN SNF.

Silver nanoparticles regulate antibiotic resistance genes by shifting bacterial community and generating anti-silver genes in estuarine biofilms

Biofilms are thought to be sinks for antibiotic resistance genes (ARGs) and nanoparticles (NPs), however, studies on the interactions between NPs and ARGs in biofilms are limited. This study focused on the occurrence and regulatory mechanisms of ARGs during the formation of biofilms with continuous treatment of zero-valent silver nanoparticles (Ag0-NPs) and Ag ions at an environmental concentration of 10 µg/L in the Yangtze Estuary. The biofilms could enrich large amounts of Ag, with the highest concentration of 97.60 mg/kg and 111.08 mg/kg in the Ag0-NPs and Ag ions group at 28 days. Compared to the blank at 28 days, the abundance of ARGs was reduced 2.2 times in the Ag0-NPs group, whereas it increased 1.3 times in the Ag ion group. Ag0-NPs and Ag ions induced the production of silver resistance genes (SRGs) or selected bacteria with SRGs in biofilms. Based on machine learning, the bacterial community, SRGs, and Ag concentration were the top three dominant regulators of ARGs, with 27.74 %, 25.57 %, and 17.93 % contributions, respectively. Structural equation modeling revealed that Ag could indirectly regulate ARGs by regulating the bacterial community in the Ag0-NPs group. Metagenomic sequencing further showed that most of the decreased ARGs were hosted by Betaproteobacteria in the Ag0-NPs groups. According to the KEGG pathway database, the possible molecular mechanism of Ag0-NPs/Ag ions regulating ARGs may be through the two-component system (arlS/silS-arlR) and beta-lactam resistance system (mexI-mexV-oprM/oprZ/smeF). Overall, this study provides new insights into the effects of Ag0-NPs at environmental concentrations on the ecological environment, especially regarding the mechanism of regulating ARGs in estuarine biofilms.

Perturbed saliva microbiome is gender-specific in patients with oral lichen planus

ObjectiveTo understand the gender characteristics of oral lichen planus (OLP) by identifying the gender-specific salivary microbiome and its potential biomarkers. MethodsA gender-based study was undertaken, commencing with the collection of saliva samples, followed by 16S rRNA gene sequencing, to explore the differences in the composition of saliva microbiome in OLP patients (40 males and 56 females) and healthy controls (40 males and 56 females), respectively. ResultsBoth male and female OLP patients had significant differences in saliva microbiome composition from healthy controls, especially in female patients. Notably, Pseudomonas was only enriched in female patients. Rhodococcus (AUC: 0.91) and Pseudomonas (AUC: 0.97) had great potential as diagnostic biomarkers in male and female patients, respectively. The KEGG results showed metabolic dysfunction was more pronounced in female patients and a high level of microbial metabolism in diverse environments, ABC transporters, Quorum sensing and Two-component system. Capnocytophaga was negatively correlated with the erosion area in male patients. Neisseria was negatively correlated with the erosion area and Rothia was positively correlated with the pain level in female patients. ConclusionsOur study revealed gender-specific perturbation in salivary microbiome within OLP patients, suggesting that the male and female patients with OLP may have different pathogenesis.

Transcriptome analysis of tilapia streptococcus agalactiae in response to baicalin.

Streptococcus agalactiae (S. agalactiae) is a highly pathogenic bacterial pathogen in aquatic animals. Our previous study has demonstrated the significant inhibitory effect of baicalin on β-hemolytic/cytolytic activity, which is a key virulence factor of S. agalactiae. In this study, we aimed to elucidate the mechanism underlying baicalin's inhibition of S. agalactiae β-hemolytic/cytolytic activity by transcriptomic analysis. Bacteria were exposed to 39.06µg/mL baicalin for 6h, and their β-hemolytic/cytolytic activities were assessed using blood plates. Then, the differentially expressed genes (DEGs) were identified and characterized by RNA sequencing (RNA-Seq), and further confirmed using the qRT-PCR. A total of 10 DEGs with 7 significantly up-regulated and 3 significantly down-regulated, were found to be affected significantly under baicalin treatment. These DEGs were associated with 5 biological processes, 5 cellular components, and 3 molecular functions. They were primarily enriched in 3 pathways: lacD and lacC in galactose metabolism, lrgA and lrgB in the two-component system, and ribH/rib4 in riboflavin metabolism. These suggested that baicalin might inhibit the conversion of pyruvate to acetyl-CoA and malonyl-CoA, which are crucial precursors for β-hemolysin/cytolysin synthesis, and result in the accumulation of pyruvate, suppress the expressions of pyruvate cell membrane channel protein genes lrgA and lrgB. Baicalin could compensatory up-regulate the expressions of tryptophan/tyrosine ABC transporter family genes, ABC.X4.A, ABC.X4.P, and ABC.X4.S by inhibiting the expression of cyl A/B in cyl operons. Moreover, it hinders the conversion of D-glucose 1-phosphate to the dTDP-L-rhamnose pathway and leads to a deficiency of L-rhamnose, an important precursor for β-hemolysin/cytolysin synthesis.

EF-hand calcium sensor, EfhP, controls transcriptional regulation of iron uptake by calcium in Pseudomonas aeruginosa.

The human pathogen Pseudomonas aeruginosa (Pa) poses a major risk for a range of severe infections, particularly lung infections in patients suffering from cystic fibrosis (CF). As previously reported, the virulent behavior of this pathogen is enhanced by elevated levels of Ca2+ that are commonly present in CF nasal and lung fluids. In addition, a Ca2+-binding EF-hand protein, EfhP (PA4107), was partially characterized and shown to be critical for the Ca2+-regulated virulence in P. aeruginosa. Here, we describe the rapid (10 min, 60 min), and adaptive (12 h) transcriptional responses of PAO1 to elevated Ca2+ detected by genome-wide RNA sequencing and show that efhP deletion significantly hindered both rapid and adaptive Ca2+ regulation. The most differentially regulated genes included multiple Fe sequestering mechanisms, a large number of extracytoplasmic function sigma factors (ECFσ), and several virulence factors, such as the production of pyocins. The Ca2+ regulation of Fe uptake was also observed in CF clinical isolates and appeared to involve the global regulator Fur. In addition, we showed that the efhP transcription is controlled by Ca2+ and Fe, and this regulation required a Ca2+-dependent two-component regulatory system CarSR. Furthermore, the efhP expression is significantly increased in CF clinical isolates and upon pathogen internalization into epithelial cells. Overall, the results established for the first time that Ca2+ controls Fe sequestering mechanisms in P. aeruginosa and that EfhP plays a key role in the regulatory interconnectedness between Ca2+ and Fe signaling pathways, the two distinct and important signaling pathways that guide the pathogen's adaptation to the host.IMPORTANCEPseudomonas aeruginosa (Pa) poses a major risk for severe infections, particularly in patients suffering from cystic fibrosis (CF). For the first time, kinetic RNA sequencing analysis identified Pa rapid and adaptive transcriptional responses to Ca2+ levels consistent with those present in CF respiratory fluids. The most highly upregulated processes include iron sequestering, iron starvation sigma factors, and self-lysis factors pyocins. An EF-hand Ca2+ sensor, EfhP, is required for at least 1/3 of the Ca2+ response, including the majority of the iron uptake mechanisms and the production of pyocins. Transcription of efhP itself is regulated by Ca2+ and Fe, and increases during interactions with host epithelial cells, suggesting the protein's important role in Pa infections. The findings establish the regulatory interconnectedness between Ca2+ and iron signaling pathways that shape Pa transcriptional responses. Therefore, understanding Pa's transcriptional response to Ca2+ and associated regulatory mechanisms will serve in the development of future therapeutics targeting Pa's dangerous infections.

Distinct Cutibacterium acnes subspecies defendens strains classified by multi-omics dissection alleviate inflammatory skin lesions of a rosacea-like mouse model

IntroductionCutibacterium acnes (C. acnes) resides in various organs such as the skin, prostate, eye, nose, stomach, and intestine, indicating the possibility of extensive crosstalk between this bacterium and the human body. C. acnes strains are classified into three subspecies based on phylogenetics and distinguishable phenotypes. Among them, C. acnes subsp. defendens strains are characterized by anti-inflammatory features, raising expectations for their potential as future microbiome therapeutics. However, the heterogeneity of C. acnes subsp. defendens and its corresponding immunological functions have not been clearly addressed.MethodsThe genetic diversity of the strains was assessed using single- and multi-locus sequence typing. Their immune-modulatory functions were evaluated in vitro using 2D and 3D assays with immune and epithelial cells. The anti-inflammatory effects were further confirmed in vivo using a rosacea-like mouse model. Comparative genomic and transcriptomic analyses were conducted to uncover mechanisms underlying the immunosuppressive activity of the strains.ResultsWe demonstrated that the newly isolated C. acnes subsp. defendens strains, exhibiting phenotypic heterogeneity, are distinctly clustered using single- and multi-locus sequence typing methods. These strains showed strong immune-regulatory functions in immune and epithelial cell-based 2D and 3D in vitro assays. Furthermore, their anti-inflammatory role was functionally confirmed in vivo using a rosacea-like mouse model, where they alleviated skin lesions characterized by hyperplasia and dermal inflammation. Comparative transcriptomics revealed that these strains may exert their immunosuppressive effects through the enhanced expression of acnecins and transcriptional variation in envelope stress regulators (specifically the two-component systems, CesSR homologs). Additionally, we propose that these C. acnes type II strains produce anti-inflammatory metabolites or peptides smaller than 3 kDa, which are associated with elevated pyrimidine and reduced L-arginine biosynthesis.DiscussionThe newly isolated C. acnes subsp. defendens strains demonstrate significant anti-inflammatory properties both in vitro and in vivo, suggesting their potential as microbiome-based therapeutics. Their unique genomic and transcriptomic profiles, including the production of small bioactive compounds and specific transcriptomic patterns, underpin their immunosuppressive capabilities. These findings provide a foundation for developing novel treatments for inflammatory skin conditions, such as rosacea.

Role of the SaeRS Two-Component Regulatory System in Group B Streptococcus Biofilm Formation on Human Fibrinogen.

Streptococcus agalactiae, also known as Group B Streptococcus or GBS, is a commensal colonizer of human vaginal and gastrointestinal tracts that can also be a deadly pathogen for newborns, pregnant women, and the elderly. The SaeRS two-component regulatory system (TCS) positively regulates the expression of two GBS adhesins genes, but its role in the formation of biofilm, an important step in pathogenesis, has not been investigated. In the present study, we set up a novel model of GBS biofilm formation using surfaces coated with human fibrinogen (hFg). Biofilm mass and structure were analyzed by crystal violet staining and three-dimensional fluorescence microscopy, respectively. GBS growth on hFg resulted in the formation of a mature and abundant biofilm composed of bacterial cells and an extracellular matrix containing polysaccharides, proteins, and extracellular DNA (eDNA). Enzymatic and genetic analysis showed that GBS biofilm formation on hFg is dependent on proteins and eDNA in the extracellular matrix and on the presence of covalently linked cell wall proteins on the bacterial surface but not on the type-specific capsular polysaccharide. In the absence of the SaeR regulator of the SaeRS TCS, there was a significant reduction in biomass formation, with reduced numbers of bacterial cells, reduced eDNA content, and disruption of the biofilm architecture. Overall, our data suggest that GBS binding to hFg contributes to biofilm formation and that the SaeRS TCS plays an important role in this process.

Heritability, signal perception and autoregulation of root nodulation in chickpea

Chickpea (Cicer arietinum L.) establishes symbiotic interactions with Mesorhizobium to develop root nodules where nitrogen fixation occurs. This symbiotic relationship can fix atmospheric nitrogen (N2) up to 140 kg N/ha that contribute nearly 80% nitrogen requirement of the crop. Global researchers had revealed the existence of natural variations in chickpea germplasm for nodulation traits with high heritability. Surprisingly, the contribution of environmental variation is too low for Biological Nitrogen Fixation (BNF) traits and high broad-sense heritability (>60) was observed for early nodulation, late nodule senescence and high nodule number traits. Correlation studies indicated a strong positive correlation between nodule number at flowering stage with total nodule weight and plant biomass and seed protein content. Nod Factor receptors in chickpea (CaNFR1 and CaNFR5) are characterized recently that forms phylogenetically distinct group along with M. truncatula, P. sativum, and L. japonicus. Critical role of cytokinin signalling through members of two component system (TCS) in nodulation was investigated in chickpea. The chickpea ortholog CaHK19 was the master spigot of cytokinin perception in chickpea. The co-expression pattern of CaHKs and CaNIN clearly indicated a link between cytokinin perception and downstream expression of CaNIN in chickpea as earlier established in Medicago. Genes involved in AON pathway are partially revealed in chickpea. CaRND1, CaRDN2, and CaRDN3 (C. arietinum Root-Determined Nodulation) function as receptors for signals produced from the roots. Revealing the molecular basis of root nodule organogenesis and their regulatory mechanisms along with identification of potential genetic stock will help on breeding or engineering chickpea genotypes with high symbiotic efficiency, extended nitrogen fixation and high symbiotic efficiency make grain legumes as nitrogen fixing factories to fertilize the soil in a sustainable way.

Transcriptomic Analysis of the Effect of Glabridin on Biofilm Formation in Staphylococcus Aureus.

Staphylococcus aureus (S. aureus) is among the major skin infection-causing pathogens in animals and humans. Its ability to form biofilms has become a foremost cause of bacterial infections and the extensive spread of drug resistance, which poses a great difficulty in clinical treatment. Glabridin (Glb), an extract of licorice with antibacterial and anti-infective properties, has a partially understood biofilm-inhibitory mechanism. This study investigated the inhibitory and antibiofilm activities of subinhibitory concentrations of Glb against S. aureus. The crystal violet assay revealed that Glb significantly suppressed biofilm expression. Scanning electron microscopy observations unveiled that Glb reduced S. aureus adhesion and accumulation by disrupting the spatial structure of the biofilm. In vitro extracellular DNA (eDNA) inhibition assays demonstrated that Glb inhibited biofilm formation by S. aureus by suppressing eDNA secretion. In total, 184 differentially expressed genes were obtained through transcriptomic (RNA-seq) sequencing, of which 81 and 103 genes were upregulated and downregulated, respectively. Glb regulated the transcript levels of biofilm-related genes through the phosphatase transfer system, two-component regulatory system, and nitrogen metabolism. The qPCR analysis was performed to confirm whether Glb interfered with the expression of regulatory genes involved in S. aureus biofilm formation (SarA, ArlR, FnbA, ClfA, icaD, and icaR) as well as the virulence gene Hla. In conclusion, this study demonstrates that Glb has a significant inhibitory effect on biofilm activity and is expected to be a good antibiofilm drug.