Polypeptide Complex Research Articles

Copper-Mediated Cross-Coupling Selective for Pyroglutamate Post-Translational Modifications.

Pyroglutamate is a cyclic N-terminal post-translational modification that occurs in both proteins and peptide hormones. The prevalence and biological roles of pyroglutamate are little understood, in part due to limited tools to identify, quantify, and manipulate its pyrrolidinone structure. Selective modification of pyroglutamate residues in complex polypeptides may provide unique tools to better understand its biological roles and to allow late-stage diversification of biologically active pyroglutamate-containing sequences. This work describes a copper-catalyzed N-H cross-coupling of unprotected peptides that is selective for N-terminal pyroglutamate residues. The reaction is operationally simple under mild conditions and tolerates all canonical residues. Mechanistic studies point to a key role for a multidentate copper-binding mode of the extended polypeptide structure in delivering the observed reactivity. The reaction allows for direct labeling and identification of a pyroglutamate hormone present in porcine intestinal extracts.

Peptide stimulation effect on organotypic culture development of neuroendocrine tissues

Introduction. One of the actual task of modern biology and medicine. Is the creation of bioregulator preparation, which can stimulate the neuroendocrine system of organism. Purpose of study. Study of effect of polypeptide complex from brain cortex (PPCbc) and from pancreas (PPCp) of calfs on the cellular proliferation in organotypic culture of nerve and endocrine of young and old rats. Methods. The adequate method of organotypic tissue culture of tissue from young and old rats was used for quick biologically activity of peptides screening. Results. The square index (SI) of nerve and endocrine tissues explants were increased statistically reliable, as compared to the control, also in young and old rats, under the polypeptides complexes effect. Conclusion. The data obtained produce the base for working and quick testing of preparations for treatment of patients with pathology in brain cortex and endocrine tissues

Silencing CCT3 induces ferroptosis through the NOD1-NF-κB signaling pathway in bladder cancer.

Bladder cancer (BCa) is a lethal malignancy of the urinary system and exhibits a poor prognosis. Chaperonin-containing tailless complex polypeptide 1 subunit 3 (CCT3) acts as an oncogene in various tumors, whereas its effect on BCa remains unknown. We identified the ferroptosis-associated differentially expressed genes through bioinformatic analysis and selected CCT3 for further verification. The levels of cell viability, apoptosis, migration, invasion, and proliferation were measured to clarify the effect of silencing CCT3 on BCa cells. Then we evaluated the role of CCT3 knockdown in vivo. Ferroptosis was assessed by the expression detection of the ferroptosis-related proteins. The underlying mechanism was predicted by RNA sequencing and verified by an agonist for nucleotide-binding and oligomerization domain 1 (NOD1). Western blotting was conducted to detect the protein expression of NOD1, nuclear factor kappa B (NF-κB) inhibitor alpha (IκBα), and phospho-IκBα (p-IκBα). In vitro, down-regulation of CCT3 suppressed the cell viability, migration, invasion, and proliferation, as well as induced apoptosis of BCa cells. In vivo, silencing CCT3 elevated the body weight of mice and suppressed the BCa progression. In addition, CCT3 knockdown could induce ferroptosis in vitro and in vivo. CCT3 knockdown suppressed the expression of NOD1 and p-IκBα/IκBα and the NOD1 agonist could reverse the effect of CCT3 suppression on BCa in vitro and in vivo. In summary, our findings demonstrate that silencing CCT3 inhibits BCa via induction of ferroptosis and suppression of the NOD1-NF-κB pathway.

Complex of Defense Polypeptides of Wheatgrass (Elytrigia elongata) Associated with Plant Immunity to Biotic and Abiotic Stress Factors.

Plant defense polypeptides play a crucial role in providing plants with constitutive immunity against various biotic and abiotic stressors. In this study, we explored a complex of proteins from wheatgrass (Elytrigia elongata) spikelets to estimate their role in the plant's tolerance to various environmental factors. The current research shows that in vitro protein extracts from E. elongata spikelets possess antifungal activity against certain Fusarium species, which are specific cereal pathogens, at concentrations of 1-2 mg/mL. In this study, we reproduced these antifungal activities using a 4 mg/mL extract in artificial fungal infection experiments on wheat grain (Triticum aestivum) under controlled laboratory conditions. Furthermore, the tested extract demonstrated a protective effect on Saccharomyces cerevisiae exposed to hyper-salinity stress at a concentration of 2 mg/mL. A combined scheme of fractionation and structural identification was applied for the estimation of the diversity of defense polypeptides. Defensins, lipid-transfer proteins, hydrolase inhibitors (cereal bifunctional trypsin/alpha-amylase inhibitors from a Bowman-Birk trypsin inhibitor), and high-molecular-weight disease resistance proteins were isolated from the extract. Thus, wheatgrass spikelets appear to be a reservoir of defense polypeptides. Our findings contribute to a deeper understanding of plant defense proteins and peptides and their involvement in the adaptation to various stress factors, and they reveal the regulatory effect at the ecosystem level.

TCP1 expression alters the ferroptosis sensitivity of diffuse large B-cell lymphoma subtypes by stabilising ACSL4 and influences patient prognosis

Diffuse large B-cell lymphoma (DLBCL), an invasive lymphoma with substantial heterogeneity, can be mainly categorised into germinal centre B-cell-like (GCB) and non-GCB subtypes. DLBCL cells are highly susceptible to ferroptosis, which offers an effective avenue for treating recurrent and refractory DLBCL. Moreover, various heat shock proteins are involved in regulating the sensitivity of tumour cells to ferroptosis. Among these proteins, tailless complex polypeptide 1 (TCP1), a subunit of chaperonin-containing T-complex protein-1 (CCT), plays a role in tumour proliferation and survival. Therefore, we explored the role of TCP1 in different DLBCL subtypes, the sensitivity of GCB and non-GCB subtypes to the ferroptosis inducer RAS-selective lethal small molecule 3 (RSL3), and the underlying molecular mechanism. In GCB cells, TCP1 promoted RSL3-induced ferroptosis. Notably, TCP1 could bind with acyl-CoA synthetase long-chain family member 4 (ACSL4), a key enzyme regulating lipid composition and facilitating ferroptosis, to reduce its ubiquitination and degradation. This interaction activated the ACSL4/LPCAT3 signalling pathway and promoted ferroptosis in the GCB subtype. However, in the non-GCB subtype, TCP1 did not act as a positive regulator but served as a predictor of an unfavourable prognosis in patients with non-GCB. In conclusion, our results suggest that in DLBCL, high TCP1 expression enhances the sensitivity of GCB tumour cells to ferroptosis and serves as a marker of poor prognosis in patients with non-GCB DLBCL.

Influence of regulatory peptides on neurogenic lower urinary tract dysfunction in multiple sclerosis. Data of one center

Objective: Cclinical evaluation of the effectiveness and safety of the effect of the regulatory polypeptide drug on neurogenic overactive bladder (OAB) in patients with multiple sclerosis (MS).Materials and methods: 41 patients with MS and urodynamically confirmed detrusor overactivity were included in a prospective, single-center, simple comparative clinical trial with sequential drug changes. The initial function of the lower urinary tract and its dynamic changes during therapy were studied by filling out a voiding diary and questionnaires using the EDSS, NBSS, SF-Qualiveen, I-QOL questionnaires. The control drug Solifenacin (patient group 1) is a specific competitive antagonist of muscarinic receptors of the M3 subtype, which causes detrusor contraction. The Study Drug (patient group 2) is a complex of regulatory polypeptides that have an organotropic effect on the bladder. Drug administration: control drug for 4 weeks, then an observation period of 4 weeks, after which - taking the Study Drug for 30 days. The results were monitored immediately after the end of taking the Study Drugs, after which they were compared with the initial data. Statistical analysis was carried out by the program “Statistica 10” (StatSoft Inc., USA), using non-parametric data analysis with median analysis, Wilcoxon test and Mann-Whitney U-test search. The results of differences were considered statistically significant if the probability of error was <5% (p<0.05).Results: Vvoiding diary: 14.6% and 24.4% of patients in groups 1 and 2, respectively, were freed from urinary incontinence; from nocturia —- 31.7% and 56.1% of patients for groups 1 and 2, respectively, the frequency of daily urination was normalized in 53.6% and 70.7% of patients in groups 1 and 2, respectively. NBSS questionnaire: decrease in the total questionnaire score by 29.2% and 47.4% for groups 1 and 2, respectively. SF-Qualiveen questionnaire: an increase in the overall assessment score by 42.3% for group 1 versus +66.5% for group 2. I-QOL questionnaire: improvement in quality of life by 56.0% and 80.4% for groups 1 and 2, respectively. The Study Drug has a higher safety profile compared to Solifenacin.Conclusion: Tthe effectiveness of the Study Drug in the correction of neurogenic OAB is higher in comparison with Solifenacin, which is reflected in a decrease in urgency, pollakiuria, the number of episodes of urinary incontinence and a significant improvement in the quality of life of these patients. The Study Drug demonstrates a high safety profile in the study.

The CCTδ subunit of the molecular chaperone CCT is required for correct localisation of p150Glued to spindle poles during mitosis

Chaperonin Containing Tailless complex polypeptide 1 (CCT) is a molecular chaperone composed of eight distinct subunits that can exist as individual monomers or as components of a double oligomeric ring, which is essential for the folding of actin and tubulin and other substrates. Here we assess the role of CCT subunits in the context of cell cycle progression by individual subunit depletions upon siRNA treatment in mammalian cells. The depletion of individual CCT subunits leads to variation in the distribution of cell cycle phases and changes in mitotic index. Mitotic defects, such as unaligned chromosomes occur when CCTδ is depleted, concurrent with a reduction in spindle pole-localised p150Glued, a component of the dynactin complex and a binding partner of monomeric CCTδ. In CCTδ-depleted cells, changes in the elution profile of p150Glued are observed consistent with altered conformations and or assembly states with the dynactin complex. Addition of monomeric CCTδ, in the form of GFP-CCTδ, restores correct p150Glued localisation to the spindle poles and rescues the mitotic segregation defects that occur when CCTδ is depleted. This study demonstrates a requirement for CCTδ in its monomeric form for correct chromosome segregation via a mechanism that promotes the correct localisation of p150Glued, thus revealing further complexities to the interplay between CCT, tubulin folding and microtubule dynamics.

Preparation and Characterization of a Hypoglycemic Complex of Gallic Acid-Antarctic Krill Polypeptide Based on Polylactic Acid-Hydroxyacetic Acid (PLGA) and High-Pressure Microjet Microencapsulation.

Gallic acid-Antarctic krill peptides (GA-AKP) nanocapsules (GA-AKP-Ns) were prepared using a dual delivery system with complex emulsion as the technical method, a high-pressure microjet as the technical means, polylactic acid-hydroxyacetic acid (PLGA) as the drug delivery vehicle, and GA-AKP as the raw material for delivery. This study aimed to investigate the effects of microjet treatment and the concentration of PLGA on the physicochemical properties and stability of the emulsion. Under optimal conditions, the physicochemical properties and hypoglycemic function of nano-microcapsules prepared after lyophilization by the solvent evaporation method were analyzed. Through the microjet treatment, the particle size of the emulsion was reduced, the stability of the emulsion was improved, and the encapsulation rate of GA-AKP was increased. The PLGA at low concentrations decreased the particle size of the emulsion, while PLGA at high concentrations enhanced the encapsulation efficiency of the emulsion. Additionally, favorable results were obtained for emulsion preparation through high-pressure microjet treatment. After three treatment cycles with a PLGA concentration of 20 mg/mL and a microjet pressure of 150 MPa (manometric pressure), the emulsion displayed the smallest particle size (285.1 ± 3.0 nm), the highest encapsulation rates of GA (71.5%) and AKP (85.2%), and optimal physical stability. GA-AKP was uniformly embedded in capsules, which can be slowly released in in vitro environments, and effectively inhibited α-amylase, α-glucosidase, and DPP-IV at different storage temperatures. This study demonstrated that PLGA as a carrier combined with microjet technology can produce excellent microcapsules, especially nano-microcapsules, and these microcapsules effectively improve the bioavailability and effectiveness of bioactive ingredients.

Efficacy of human placenta hydrolyzate in the treatment of patients with metabolic associated fatty liver disease at the stage of fibrosis (pilot study)

Background. Despite active research, drug treatment options for metabolic associated fatty liver disease (MAFLD) are limited, and there are no currently approved drugs for patients with MAFLD. Treatment of patients at risk of developing non-alcoholic steatohepatitis and progressive liver fibrosis (LF) is of particular relevance, since they determine the clinical outcomes of the disease.
 Aim. To evaluate the clinical efficacy of complex polypeptide drug (CPD), human placenta hydrolyzate, containing low molecular weight regulatory peptides, amino acids, vitamins, macro- and microelements in patients with MAFLD at the LF stage.
 Materials and methods. A single-center, placebo-controlled pilot study. Patients with MAFLD at LF stage 1≤F≤3 according to METAVIR were included (n=10, of which 8 were women, median age was 55 years old). Patients were randomized into 2 groups: 5 people received CPD therapy for 12 weeks (intravenous infusion of 6 ml 2 times a week); another 5 people initially received placebo x 2 times a week (12 weeks), with transfer to the open phase for CPD therapy in the same regimen. The dynamics laboratory and instrumental data was assessed, as well as determine the presence of fibrosis by non-invasive tests – measurement of liver stiffness by transient elastography and use of serum biomarker (SM) by FibroTest and detection of steatosis with controlled attenuation parameter for transient elastography and SM by SteatoTest. The quality of life of patients was assessed using questionnaire SF-36 and well-being via Visual Analogue Scale. Statistical processing of the material was carried out using the methods of nonparametric analysis, using the Statistica 13.3 software.
 Results. Patients in the CPD group compared with the baseline data and with the placebo group showed a statistically significant improvement: 1) transaminases (ALT, AST), lipid profile indicators (cholesterol), ferritin; 2) indicators of LF, based on a decrease in liver stiffness by transient elastography and SM of Fibrotest, as well as the degree of steatosis based on controlled attenuation parameter and SM of Steatotest; 3) in well-being and quality of life (according to testing: SF-36 physical, mental well-being and general condition of the VAS). CPD was well tolerated, no side effects were noted.
 Conclusion. In patients with MAFLD during CPD therapy, a decrease in the level of liver enzymes was noted, as well as in LF and liver steatosis according to noninvasive methods. Randomized controlled trials are required to confirm these findings.

The Function of Different Subunits of the Molecular Chaperone CCT in the Microsporidium Nosema bombycis: NbCCTζ Interacts with NbCCTα.

Chaperonin containing tailless complex polypeptide 1 (CCT) is a molecular chaperone protein that consists of eight completely different subunits and assists in the folding of newly synthesized peptides. The zeta subunit of CCT is a regulatory factor for the folding and assembly of cytoskeletal proteins as individuals or complexes. In this study, the zeta subunit of Nosema bombycis (NbCCTζ) is identified for the first time. The complete ORF of the NbCCTζ gene is 1533 bp in length and encodes a 510 amino acid polypeptide. IFA results indicate that NbCCTζ is colocalized with actin and β-tubulin in the cytoplasm during the proliferative phase and that NbCCTζ is completely colocalized with NbCCTα in the cytoplasm of N. bombycis throughout the entire life cycle. Furthermore, the yeast two-hybrid assay revealed that the NbCCTζ interacts with NbCCTα. The transcriptional level of NbCCTζ is significantly downregulated by knocking down the NbCCTα gene, while the transcriptional level of NbCCTα is downregulated after knocking down the NbCCTζ gene. These results suggest that NbCCTζ may play a vital role in the proliferation of N. bombycis by coordinating with NbCCTα.

The recruitment of TRiC chaperonin in rotavirus viroplasms correlates with virus replication.

The replication of rotavirus takes place in cytosolic inclusions termed viroplasms. In these inclusions, the distinct 11 double-stranded RNA genome segments are co-packaged to complete a genome in newly generated virus particles. In this study, we show for the first time that the tailless complex polypeptide I ring complex (TRiC), a cellular chaperonin responsible for the folding of at least 10% of the cytosolic proteins, is a component of viroplasms and is required for the synthesis of the viral negative-sense single-stranded RNA. Specifically, TRiC associates with NSP5 and VP2, the cofactor involved in RNA replication. Our study adds a new component to the current model of rotavirus replication, where TRiC is recruited to viroplasms to assist replication.

ПРОТЕКТИВНОЕ ВЛИЯНИЕ НООКЛЕРИНА И СЛАВИНОРМА НА КАРДИОРЕСПИРАТОРНЫЕ ФУНКЦИИ КРЫС ПРИ ОХЛАЖДЕНИИ В ВОДЕ

Effects of nooclerin (deanol aceglumate) and slavinorm (vascular polypeptide complex) on the breathing and heart rates were compared in Wistar rats in the course of progressive hypothermia. The animals were immersed in water at 9 ± 0.4 °С. The parameters under study were breathing rate (BR), heart rate (HR), rectal temperature (Тr), esophageal temperature (Tes), and arterial saturation (SpO2). In comparison to controls, at the beginning of hypothermia BR in experimental rats was high at lower Tr values. Nooclerin did not change the trend of HR curve dependence on Tr, whereas slavinorm shifted the trend toward high HR values; besides, it more than doubled life duration before the respiratory arrest. This occurred as a result of rats' transition in the state of cold-hypometabolism when the cardiac activity was maintained by slow breathing. The investigation showed that nooclerin and slavinorm are able to preserve the viability of organisms in hypothermic environment. Both drugs enhance and extend the stage of breathing activation at the beginning of cold immersion in the experimental rats in comparison to their controls. Injection of nooclerin and slavinorm mobilizes the defenses of organism and reduces the pathological effects of deep hypothermia.

Unravelling the potential of yolkin for nutraceutical use: the origin, structure, and functional insights of a hen egg yolk polypeptide complex.

Nutraceuticals can reduce the risk of many diseases, such as cardiovascular disease, immune deficiencies, neurodegeneration, and others. Their delivery remains a challenge because it depends on many factors, most notably the stability of the bioactive compounds. Yolkin is a peptide complex isolated from hen egg yolk with immunomodulatory and neuroprotective potential. However, yolkin remains relatively poorly characterized. We aimed to determine the origin and glycosylation level of yolkin, its storage conditions, its thermal stability, and its aggregation ability and to assess its antioxidant, antihypertensive, and antidiabetic potential. The peptide composition of yolkin was shown to be homologous to that of vitellogenin II and vitellogenin I. These results indicate the stability of yolkin in a lyophilized form, preferably at 4 °C, with nonaggregation, antioxidant, and antidiabetic activities. As a result, yolkin can be considered to have significant therapeutic potential and represents a valuable tool for the development of novel nutraceuticals.

CCT6A functions as promising diagnostic biomarker and promotes cell proliferation in colorectal cancer.

Background: Chaperonin-containing tailless complex polypeptide 1 subunit 6A (CCT6A) is mainly located in the cytoplasm and considered to be involved in various biological processes in tumors. However, its function and the intrinsic mechanism need to be further elucidated. Methods: Multi-omics analysis was used to evaluate the correlation between CCT6A expression and prognosis of patients, as well as its immune value. CCT6A was knockout by CRISPR-Cas9, and overexpressed by transfecting plasmids in colorectal cancer (CRC) cells. Cell proliferation was analyzed by MTS, EDU staining and colony growth assay, and cell migration was monitored by wound healing assay and Transwell assay. The phosphor-kinase array kit and immunoblotting assay was utilized to explore the potential molecular mechanisms. Results: CCT6A was highly expressed in multiple tumor tissues and significantly correlated with the prognosis of patients. It was also associated with the immune infiltration, immune correlation and prognosis in CRC. CCT6A was highly expressed in CRC biopsies as well as fresh CRC tissues. Meanwhile, knockout of CCT6A reduced cell proliferation, cell cycle and cell migration. On the contrary, overexpression of CCT6A exhibited the opposite phenotypes. Moreover, we identified that HSPD1 and non-phosphorylated P53 were highly increased in CCT6A overexpressed cells, which are involved in regulating tumorigenesis. Conclusions: Therefore, CCT6A positively regulated cell proliferation/migration in CRC cells, and suggesting CCT6A has a high immunological value and is associated with CRC progression, which makes it a potential therapeutic target for CRC.

Design Rules for the Sequestration of Viruses into Polypeptide Complex Coacervates.

Encapsulation is a strategy that has been used to facilitate the delivery and increase the stability of proteins and viruses. Here, we investigate the encapsulation of viruses via complex coacervation, which is a liquid-liquid phase separation resulting from the complexation of oppositely charged polymers. In particular, we utilized polypeptide-based coacervates and explored the effects of peptide chemistry, chain length, charge patterning, and hydrophobicity to better understand the effects of the coacervating polypeptides on virus incorporation. Our study utilized two nonenveloped viruses, porcine parvovirus (PPV) and human rhinovirus (HRV). PPV has a higher charge density than HRV, and they both appear to be relatively hydrophobic. These viruses were compared to characterize how the charge, hydrophobicity, and patterning of chemistry on the surface of the virus capsid affects encapsulation. Consistent with the electrostatic nature of complex coacervation, our results suggest that electrostatic effects associated with the net charge of both the virus and polypeptide dominated the potential for incorporating the virus into a coacervate, with clustering of charges also playing a significant role. Additionally, the hydrophobicity of a virus appears to determine the degree to which increasing the hydrophobicity of the coacervating peptides can enhance virus uptake. Nonintuitive trends in uptake were observed with regard to both charge patterning and polypeptide chain length, with these parameters having a significant effect on the range of coacervate compositions over which virus incorporation was observed. These results provide insights into biophysical mechanisms, where sequence effects can control the uptake of proteins or viruses into biological condensates and provide insights for use in formulation strategies.

Yolkin, a Polypeptide Complex from Egg Yolk, Affects Cytokine Levels and Leukocyte Populations in Broiler Chicken Blood and Lymphoid Organs after In Ovo Administration.

Yolkin is a polypeptide complex isolated from hen egg yolk that exhibits immunomodulating properties. The aim of the present study was to determine whether in-ovo-delivered yolkin affects leukocyte populations and cytokine levels in broiler chickens. The experiment was carried out on eggs from Ross 308 broiler breeder birds. Yolkin was administered in ovo on the 18th day of incubation, once, at the following three doses: 1, 10, or 100 µg/egg. The immunological parameters were assessed in 1-, 7-, 14-, 21-, 28-, 35-, and 42-day-old birds kept under farming conditions and routinely vaccinated. The leukocyte populations were determined in the thymus, spleen, and blood. The cytokine (IL-1β, IL-2, IL-6, and IL-10) levels were determined in the plasma of the broiler chickens. Each experimental group included eight birds. The most pronounced effect of yolkin was an increase in the population of T cells, both CD4+ and CD8+, mainly in the blood. This effect on the lymphocyte subsets may be valuable regarding chicken immune responses, mainly against T-dependent antigens, during infection or after vaccination.

Evaluation of Polypeptide Complexes from Marine Sources with Relevance in Initiation and Propagation Mechanisms of Osteoarticular Dysfunctions

The aim of the present study was to obtain a protein fraction rich in enzymes with proteolytic activity such as serine proteases, chymotrypsins and cysteine proteases and to investigate preliminary pharmacological effects with therapeutic potential in osteoarticular diseases. The processing of marine raw material by applying established and optimized sequences of operations (selective precipitation followed by fractionation by FPLC) led to well-defined protein fractions rich in proteolytic enzymes. To evaluate the biological effect of the isolated polypeptide fractions, an in vitro model on normal human osteoblast (HOB) and osteoarthritic (HOB-OA) cell lines was carried out in which the modulation of cell proliferation under the action of the polypeptide complexes was followed.

An Algorithm for the Development of a Recombinant Antiherpetic Subunit Vaccine Combining the Crystal Structure Analysis, AlphaFold2-Based Modeling, and Immunoinformatics

Using the envelope glycoprotein B (gB) crystal structure and digital prediction algorithm, the B- and T-cell antigenic determinants (epitopes) of human herpesvirus 1 (HHV-1), also known as herpes simplex virus 1 (HSV-1), were generated, and the method for their production in the form of recombinant proteins was proposed. First, the structure of the surface topological domain (ectodomain or spike) of gB with mapped epitopes was analyzed, and the most stable and immunogenic (due to their enrichment with B-and T-cell epitopes) subdomains were selected for the modeling of subunit vaccine prototypes using the AlphaFold2 (Google DeepMind, London, UK) artificial intelligence system. The proposed candidate vaccines included both small (about 100 amino acids) monomeric polypeptides, which were ideal for recombinant expression as fusion proteins, and a more complex polypeptide, which, due to its trimeric fold, looks like a miniature analog of the gB ectodomain. In this miniature analog, the ectodomain regions with the potential to interfere efficacious expression of soluble recombinant protein in Escherichia coli have been removed. The structural stability of the modeled proteins, confirmed by molecular dynamics simulation and host immune responses, predicted in silico, indicates the suitability of the two suggested polypeptides for generating subunit vaccines using recombinant DNA technology.

The role of the Mediator complex in fungal pathogenesis and response to antifungal agents.

Mediator is a complex of polypeptides that plays a central role in the recruitment of RNA polymerase II to promoters and subsequent transcriptional activation in eukaryotic organisms. Studies have now shown that Mediator has a role in regulating expression of genes implicated in virulence and antifungal drug resistance in pathogenic fungi. The roles of specific Mediator subunits have been investigated in several species of pathogenic fungi, particularly in the most pathogenic yeast Candida albicans. Uniquely, pathogenic yeast also present several interesting examples of divergence in Mediator structure and function, most notably in C. glabrata, which possesses two orthologues of Med15, and in C. albicans, which has a massively expanded family of Med2 orthologues known as the TLO gene family. This review highlights specific examples of recent progress in characterizing the role of Mediator in pathogenic fungi.

Prefoldin 2 contributes to mitochondrial morphology and function

BackgroundPrefoldin is an evolutionarily conserved co-chaperone of the tailless complex polypeptide 1 ring complex (TRiC)/chaperonin containing tailless complex 1 (CCT). The prefoldin complex consists of six subunits that are known to transfer newly produced cytoskeletal proteins to TRiC/CCT for folding polypeptides. Prefoldin function was recently linked to the maintenance of protein homeostasis, suggesting a more general function of the co-chaperone during cellular stress conditions. Prefoldin acts in an adenosine triphosphate (ATP)-independent manner, making it a suitable candidate to operate during stress conditions, such as mitochondrial dysfunction. Mitochondrial function depends on the production of mitochondrial proteins in the cytosol. Mechanisms that sustain cytosolic protein homeostasis are vital for the quality control of proteins destined for the organelle and such mechanisms among others include chaperones.ResultsWe analyzed consequences of the loss of prefoldin subunits on the cell proliferation and survival of Saccharomyces cerevisiae upon exposure to various cellular stress conditions. We found that prefoldin subunits support cell growth under heat stress. Moreover, prefoldin facilitates the growth of cells under respiratory growth conditions. We showed that mitochondrial morphology and abundance of some respiratory chain complexes was supported by the prefoldin 2 (Pfd2/Gim4) subunit. We also found that Pfd2 interacts with Tom70, a receptor of mitochondrial precursor proteins that are targeted into mitochondria.ConclusionsOur findings link the cytosolic prefoldin complex to mitochondrial function. Loss of the prefoldin complex subunit Pfd2 results in adaptive cellular responses on the proteome level under physiological conditions suggesting a continuous need of Pfd2 for maintenance of cellular homeostasis. Within this framework, Pfd2 might support mitochondrial function directly as part of the cytosolic quality control system of mitochondrial proteins or indirectly as a component of the protein homeostasis network.