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Petchiappan A, Majdalani N, Wall E, Gottesman S. RcsF-independent mechanisms of signaling within the Rcs Phosphorelay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.29.610257. [PMID: 39372736 PMCID: PMC11451591 DOI: 10.1101/2024.08.29.610257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/08/2024]
Abstract
The Rcs (regulator of capsule synthesis) phosphorelay is a conserved cell envelope stress response mechanism in enterobacteria. It responds to perturbations at the cell surface and the peptidoglycan layer from a variety of sources, including antimicrobial peptides, beta-lactams, and changes in osmolarity. RcsF, an outer membrane lipoprotein, is the sensor for this pathway and activates the phosphorelay by interacting with an inner membrane protein IgaA. IgaA is essential; it negatively regulates the signaling by interacting with the phosphotransferase RcsD. We previously showed that RcsF-dependent signaling does not require the periplasmic domain of the histidine kinase RcsC and identified a dominant negative mutant of RcsD that can block signaling via increased interactions with IgaA. However, how the inducting signals are sensed and how signal is transduced to activate the transcription of the Rcs regulon remains unclear. In this study, we investigated how the Rcs cascade functions without its only known sensor, RcsF and characterized the underlying regulatory mechanisms for three distinct RcsF-independent inducers. Previous reports showed that Rcs signaling can be induced in the absence of RcsF by a loss of function mutation in the periplasmic oxidoreductase DsbA or by overexpression of the DnaK cochaperone DjlA. We identified an inner membrane protein, DrpB, as a multicopy RcsF-independent Rcs activator in E. coli . The loss of the periplasmic oxidoreductase DsbA and the overexpression of the DnaK cochaperone DjlA each trigger the Rcs cascade in the absence of RcsF by weakening IgaA-RcsD interactions in different ways. In contrast, the cell-division associated protein DrpB uniquely requires the RcsC periplasmic domain for signaling; this domain is not needed for RcsF-dependent signaling. This suggests the possibility that RcsC acts as a sensor for some Rcs signals. Overall, the results add new understanding to how this complex phosphorelay can be activated by diverse mechanisms. Author summary The Rcs phosphorelay signaling cascade regulates the expression of genes related to capsule synthesis, biofilm formation, virulence, and cell division in Enterobacteria and is critical for cell membrane integrity and response to beta-lactam antibiotics and antimicrobial peptides. RcsF is the sole known sensor, but other proteins have been reported to activate this pathway in the absence of RcsF. We have discovered a novel RcsF-independent Rcs activator and found that each of three RcsF-independent proteins activate the system differently. Most significantly, we find that the histidine kinase RcsC can be involved in signal sensing independently of RcsF. Our study sheds light into the complex mechanisms of Rcs activation and adds to our knowledge of non-orthodox signaling systems across organisms.
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Costafrolaz J, Panis G, Casu B, Ardissone S, Degeorges L, Pilhofer M, Viollier PH. Adaptive β-lactam resistance from an inducible efflux pump that is post-translationally regulated by the DjlA co-chaperone. PLoS Biol 2023; 21:e3002040. [PMID: 38051727 PMCID: PMC10754441 DOI: 10.1371/journal.pbio.3002040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 12/28/2023] [Accepted: 10/19/2023] [Indexed: 12/07/2023] Open
Abstract
The acquisition of multidrug resistance (MDR) determinants jeopardizes treatment of bacterial infections with antibiotics. The tripartite efflux pump AcrAB-NodT confers adaptive MDR in the polarized α-proteobacterium Caulobacter crescentus via transcriptional induction by first-generation quinolone antibiotics. We discovered that overexpression of AcrAB-NodT by mutation or exogenous inducers confers resistance to cephalosporin and penicillin (β-lactam) antibiotics. Combining 2-step mutagenesis-sequencing (Mut-Seq) and cephalosporin-resistant point mutants, we dissected how TipR uses a common operator of the divergent tipR and acrAB-nodT promoter for adaptive and/or potentiated AcrAB-NodT-directed efflux. Chemical screening identified diverse compounds that interfere with DNA binding by TipR or induce its dependent proteolytic turnover. We found that long-term induction of AcrAB-NodT deforms the envelope and that homeostatic control by TipR includes co-induction of the DnaJ-like co-chaperone DjlA, boosting pump assembly and/or capacity in anticipation of envelope stress. Thus, the adaptive MDR regulatory circuitry reconciles drug efflux with co-chaperone function for trans-envelope assemblies and maintenance.
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Affiliation(s)
- Jordan Costafrolaz
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Bastien Casu
- Department of Biology, Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Silvia Ardissone
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Laurence Degeorges
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Martin Pilhofer
- Department of Biology, Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland
| | - Patrick H. Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine/Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
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Liang J, Cameron G, Faucher SP. Development of heat-shock resistance in Legionella pneumophila modeled by experimental evolution. Appl Environ Microbiol 2023; 89:e0066623. [PMID: 37668382 PMCID: PMC10537758 DOI: 10.1128/aem.00666-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/29/2023] [Indexed: 09/06/2023] Open
Abstract
Because it can grow in buildings with complex hot water distribution systems (HWDS), healthcare facilities recognize the waterborne bacterium Legionella pneumophila as a major nosocomial infection threat and often try to clear the systems with a pasteurization process known as superheat-and-flush. After this treatment, many facilities find that the contaminating populations slowly recover, suggesting the possibility of in situ evolution favoring increased survival in high-temperature conditions. To mimic this process in a controlled environment, an adaptive laboratory evolution model was used to select a wild-type strain of L. pneumophila for survival to transient exposures to temperatures characteristic of routine hot water use or failed pasteurization processes in HWDS. Over their evolution, these populations became insensitive to exposure to 55°C and developed the ability to survive short exposures to 59°C heat shock. Heat-adapted lineages maintained a higher expression of heat-shock genes during low-temperature incubation in freshwater, suggesting a pre-adaptation to heat stress. Although there were distinct mutation profiles in each of the heat-adapted lineages, each acquired multiple mutations in the DnaJ/DnaK/ClpB disaggregase complex, as well as mutations in chaperone htpG and protease clpX. These mutations were specific to heat-shock survival and were not seen in control lineages included in the experimental model without exposure to heat shock. This study supports in situ observations of adaptation to heat stress and demonstrates the potential of L. pneumophila to develop resistance to control measures. IMPORTANCE As a bacterium that thrives in warm water ecosystems, Legionella pneumophila is a key factor motivating regulations on hot water systems. Two major measures to control Legionella are high circulating temperatures intended to curtail growth and the use of superheat-and-flush pasteurization processes to eliminate established populations. Facilities often suffer recolonization of their hot water systems; hospitals are particularly at risk due to the severe nosocomial pneumoniae caused by Legionella. To understand these long-term survivors, we have used an adaptive laboratory evolution model to replicate this process. We find major differences between the mutational profiles of heat-adapted and heat-naïve L. pneumophila populations including mutations in major heat-shock genes like chaperones and proteases. This model demonstrates that well-validated treatment protocols are needed to clear contaminated systems and-in an analog to antibiotic resistance-the importance of complete eradication of the resident population to prevent selection for more persistent bacteria.
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Affiliation(s)
- Jeffrey Liang
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Gillian Cameron
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Sébastien P. Faucher
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada
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CleanSeq: A Pipeline for Contamination Detection, Cleanup, and Mutation Verifications from Microbial Genome Sequencing Data. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12126209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Contaminations frequently occur in bacterial cultures, which significantly affect the reproducibility and reliability of the results from whole-genome sequencing (WGS). Decontaminated WGS data with clean reads is the only desirable source for detecting possible variants correctly. Improvements in bioinformatics are essential to analyze the contaminated WGS dataset. Existing pipelines usually contain contamination detection, decontamination, and variant calling separately. The efficiency and results from existing pipelines fluctuate since distinctive computational models and parameters are applied. It is then promising to develop a bioinformatical tool containing functions to discriminate and remove contaminated reads and improve variant calling from clean reads. In this study, we established a Python-based pipeline named CleanSeq for automatic detection and removal of contaminating reads, analyzing possible genome variants with proper verifications via local re-alignments. The application and reproducibility are proven in either simulated, publicly available datasets or actual genome sequencing reads from our experimental evolution study in Escherichia coli. We successfully obtained decontaminated reads, called out all seven consistent mutations from the contaminated bacterial sample, and derived five colonies. Collectively, the results demonstrated that CleanSeq could effectively process the contaminated samples to achieve decontaminated reads, based on which reliable results (i.e., variant calling) could be obtained.
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Hierarchical Model for the Role of J-Domain Proteins in Distinct Cellular Functions. J Mol Biol 2020; 433:166750. [PMID: 33310019 DOI: 10.1016/j.jmb.2020.166750] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 12/04/2020] [Accepted: 12/04/2020] [Indexed: 01/28/2023]
Abstract
In Escherichia coli, the major bacterial Hsp70 system consists of DnaK, three J-domain proteins (JDPs: DnaJ, CbpA, and DjlA), and nucleotide exchange factor GrpE. JDPs determine substrate specificity for the Hsp70 system; however, knowledge on their specific role in bacterial cellular functions is limited. In this study, we demonstrated the role of JDPs in bacterial survival during heat stress and the DnaK-regulated formation of curli-extracellular amyloid fibers involved in biofilm formation. Genetic analysis demonstrate that only DnaJ is essential for survival at high temperature. On the other hand, either DnaJ or CbpA, but not DjlA, is sufficient to activate DnaK in curli production. Additionally, several DnaK mutants with reduced activity are able to complement the loss of curli production in E. coli ΔdnaK, whereas they do not recover the growth defect of the mutant strain at high temperature. Biochemical analyses reveal that DnaJ and CbpA are involved in the expression of the master regulator CsgD through the solubilization of MlrA, a DNA-binding transcriptional activator for the csgD promoter. Furthermore, DnaJ and CbpA also keep CsgA in a translocation-competent state by preventing its aggregation in the cytoplasm. Our findings support a hierarchical model wherein the role of JDPs in the Hsp70 system differs according to individual cellular functions.
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Steenhuis M, ten Hagen-Jongman CM, van Ulsen P, Luirink J. Stress-Based High-Throughput Screening Assays to Identify Inhibitors of Cell Envelope Biogenesis. Antibiotics (Basel) 2020; 9:antibiotics9110808. [PMID: 33202774 PMCID: PMC7698014 DOI: 10.3390/antibiotics9110808] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 11/16/2022] Open
Abstract
The structural integrity of the Gram-negative cell envelope is guarded by several stress responses, such as the σE, Cpx and Rcs systems. Here, we report on assays that monitor these responses in E. coli upon addition of antibacterial compounds. Interestingly, compromised peptidoglycan synthesis, outer membrane biogenesis and LPS integrity predominantly activated the Rcs response, which we developed into a robust HTS (high-throughput screening) assay that is suited for phenotypic compound screening. Furthermore, by interrogating all three cell envelope stress reporters, and a reporter for the cytosolic heat-shock response as control, we found that inhibitors of specific envelope targets induce stress reporter profiles that are distinct in quality, amplitude and kinetics. Finally, we show that by using a host strain with a more permeable outer membrane, large-scaffold antibiotics can also be identified by the reporter assays. Together, the data suggest that stress profiling is a useful first filter for HTS aimed at inhibitors of cell envelope processes.
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Liu B, Hou W, Li K, Chen Q, Liu Y, Yue T. Specific gene SEN1393 contributes to higher survivability of Salmonella Enteritidis in egg white by regulating sulfate assimilation pathway. Int J Food Microbiol 2020; 337:108927. [PMID: 33152571 DOI: 10.1016/j.ijfoodmicro.2020.108927] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 11/16/2022]
Abstract
Salmonella enterica serovar Enteritidis (S. Enteritidis) presents an excellent capacity to survive in egg white, which is a hostile environment for bacterial growth. To reveal its survival mechanism, this study focuses on the specific gene SEN1393, which has been found to exist only in the genomic sequence of S. Enteritidis. The survival capacity of the deletion mutant strain ΔSEN1393 was proven to be significantly reduced after incubation in egg white. RNA sequencing and RT-qPCR results demonstrate that the expression levels of 19 genes were up-regulated, while the expression levels of 9 genes were down-regulated in egg white. These genes were classified into 6 groups based on their functional categories, namely the sulfate assimilation pathway, arginine biosynthesis, the tricarboxylic acid cycle, the fimbrial protein, the transport and chelation of metal ion, and others (sctT, rhs, and pspG). The strain ΔSEN1393 was deduced to damage FeS cluster enzymes and increase the sulfate and iron requirements, and to reduce bacterial motility and copper homeostasis. Via InterProScan analysis, the gene SEN1393 was speculated to encode a TerB-like and/or DjlA-like protein, and therefore, together with cysJ, possibly reduced the oxidative toxicities resulting from oxyanions such as tellurite, and/or improved CysPUWA conformation to restrain the uptake of the toxic oxyanions. In summary, the gene SEN1393 enabled the higher survival of S. Enteritidis in egg white as compared to other pathogens by regulating the sulfate assimilation pathway.
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Affiliation(s)
- Bin Liu
- College of Food Science and Engineering, Northwest A&F University, Yangling, China; Laboratory of Quality and Safety Risk Assessment for Agro-Products, Ministry of Agriculture, Yangling, China; National Engineering Research Center of Agriculture Integration Test, Yangling, China.
| | - Wanwan Hou
- College of Food Science and Engineering, Northwest A&F University, Yangling, China; Laboratory of Quality and Safety Risk Assessment for Agro-Products, Ministry of Agriculture, Yangling, China; National Engineering Research Center of Agriculture Integration Test, Yangling, China
| | - Ke Li
- Zhejiang Academy of Science & Technology for Inspection & Quarantine, Hangzhou, China
| | - Qing Chen
- College of Food Science and Engineering, Northwest A&F University, Yangling, China; Laboratory of Quality and Safety Risk Assessment for Agro-Products, Ministry of Agriculture, Yangling, China; National Engineering Research Center of Agriculture Integration Test, Yangling, China
| | - Yaxin Liu
- College of Food Science and Engineering, Northwest A&F University, Yangling, China; Laboratory of Quality and Safety Risk Assessment for Agro-Products, Ministry of Agriculture, Yangling, China; National Engineering Research Center of Agriculture Integration Test, Yangling, China
| | - Tianli Yue
- College of Food Science and Engineering, Northwest A&F University, Yangling, China; Laboratory of Quality and Safety Risk Assessment for Agro-Products, Ministry of Agriculture, Yangling, China; National Engineering Research Center of Agriculture Integration Test, Yangling, China
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Barriot R, Latour J, Castanié-Cornet MP, Fichant G, Genevaux P. J-Domain Proteins in Bacteria and Their Viruses. J Mol Biol 2020; 432:3771-3789. [DOI: 10.1016/j.jmb.2020.04.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 02/06/2023]
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Michou M, Stergios A, Skretas G. SuptoxD2.0: A second-generation engineered Escherichia coli strain achieving further enhanced levels of recombinant membrane protein production. Biotechnol Bioeng 2020; 117:2434-2445. [PMID: 32383198 DOI: 10.1002/bit.27378] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/05/2020] [Accepted: 05/06/2020] [Indexed: 11/10/2022]
Abstract
The bacterium Escherichia coli is among the most popular hosts for recombinant protein production, including that of membrane proteins (MPs). We have recently generated the specialized MP-producing E. coli strain SuptoxD, which upon co-expression of the effector gene djlA, is capable of alleviating two major bottlenecks in bacterial recombinant MP production: it suppresses the toxicity that frequently accompanies the MP-overexpression process and it markedly increases the cellular accumulation of membrane incorporated and properly folded recombinant MP. Combined, these two positive effects result in dramatically enhanced volumetric yields for various recombinant MPs of both prokaryotic and eukaryotic origin. Based on the observation that djlA is found in the genomes of various pathogenic bacteria, the aim of the present work was to investigate (a) whether other naturally occurring DjlA variants can exert the MP toxicity-suppressing and production-promoting effects similarly to the E. coli DjlA and (b) if we can identify a DjlA variant whose efficiency surpasses that of the E. coli DjlA of SuptoxD. We report that a quite surprisingly broad variety of homologous DjlA proteins exert beneficial effects on recombinant MP when overexpressed in E. coli. Furthermore, we demonstrate that the Salmonella enterica DjlA is an even more potent enhancer of MP productivity compared with the E. coli DjlA of SuptoxD. Based on this, we constructed a second-generation SuptoxD strain, termed SuptoxD2.0, whose MP-production capabilities surpass significantly those of the original SuptoxD, and we anticipate that SuptoxD2.0 will become a broadly utilized expression host for recombinant MP production in bacteria.
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Affiliation(s)
- Myrsini Michou
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece.,Department of Biochemistry and Biotechnology, University of Thessaly, Larisa, Greece
| | - Angelos Stergios
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece.,Department of Biological Applications and Technology, University of Ioannina, Ioannina, Greece
| | - Georgios Skretas
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece
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10
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Kiu R, Caim S, Painset A, Pickard D, Swift C, Dougan G, Mather AE, Amar C, Hall LJ. Phylogenomic analysis of gastroenteritis-associated Clostridium perfringens in England and Wales over a 7-year period indicates distribution of clonal toxigenic strains in multiple outbreaks and extensive involvement of enterotoxin-encoding (CPE) plasmids. Microb Genom 2019; 5. [PMID: 31553300 PMCID: PMC6861862 DOI: 10.1099/mgen.0.000297] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Clostridium perfringens is a major enteric pathogen known to cause gastroenteritis in human adults. Although major outbreak cases are frequently reported, only limited whole-genome sequencing (WGS) based studies have been performed to understand the genomic epidemiology and virulence gene content of outbreak-associated C. perfringens strains. We performed phylogenomic analysis on 109 C. perfringens isolates (human and food) obtained from disease cases in England and Wales between 2011 and 2017. Initial findings highlighted the enhanced discriminatory power of WGS in profiling outbreak C. perfringens strains, when compared to the current Public Health England referencing laboratory technique of fluorescent amplified fragment length polymorphism analysis. Further analysis identified that isogenic C. perfringens strains were associated with nine distinct care-home-associated outbreaks over the course of a 5-year interval, indicating a potential common source linked to these outbreaks or transmission over time and space. As expected, the enterotoxin cpe gene was encoded in all but 4 isolates (96.3 %; 105/109), with virulence plasmids encoding cpe (particularly pCPF5603 and pCPF4969 plasmids) extensively distributed (82.6 %; 90/109). Genes encoding accessory virulence factors, such as beta-2 toxin, were commonly detected (46.7 %; 51/109), and genes encoding phage proteins were also frequently identified. Overall, this large-scale genomic study of gastroenteritis-associated C. perfringens suggested that three major cpe-encoding (toxinotype F) genotypes underlie these outbreaks: strains carrying (1) pCPF5603 plasmid, (2) pCPF4969 plasmid and (3) chromosomal-cpe strains. Our findings substantially expanded our knowledge on type F C. perfringens involved in human-associated gastroenteritis, with further studies required to fully probe the dissemination and regional reservoirs of this enteric pathogen, which may help devise effective prevention strategies to reduce the food-poisoning disease burden in vulnerable patients, such as the elderly.
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Affiliation(s)
- Raymond Kiu
- Gut Microbes and Health, Quadram Institute Bioscience, Norwich NR4 7UQ, UK
| | - Shabhonam Caim
- Gut Microbes and Health, Quadram Institute Bioscience, Norwich NR4 7UQ, UK
| | - Anais Painset
- Gastrointestinal Bacteria Reference Unit, Public Health England, London NW9 5EQ, UK
| | - Derek Pickard
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Craig Swift
- Gastrointestinal Bacteria Reference Unit, Public Health England, London NW9 5EQ, UK
| | - Gordon Dougan
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Alison E Mather
- Faculty of Medicine and Health Sciences, University of East Anglia, Norwich NR4 7TJ, UK.,Microbes in the Food Chain, Quadram Institute Bioscience, Norwich NR4 7UQ, UK
| | - Corinne Amar
- Gastrointestinal Bacteria Reference Unit, Public Health England, London NW9 5EQ, UK
| | - Lindsay J Hall
- Gut Microbes and Health, Quadram Institute Bioscience, Norwich NR4 7UQ, UK
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Abstract
RcsB, a response regulator of the FixJ/NarL family, is at the center of a complex network of regulatory inputs and outputs. Cell surface stress is sensed by an outer membrane lipoprotein, RcsF, which regulates interactions of the inner membrane protein IgaA, lifting negative regulation of a phosphorelay. In vivo evidence supports a pathway in which histidine kinase RcsC transfers phosphate to phosphotransfer protein RcsD, resulting in phosphorylation of RcsB. RcsB acts either alone or in combination with RcsA to positively regulate capsule synthesis and synthesis of small RNA (sRNA) RprA as well as other genes, and to negatively regulate motility. RcsB in combination with other FixJ/NarL auxiliary proteins regulates yet other functions, independent of RcsB phosphorylation. Proper expression of Rcs and its targets is critical for success of Escherichia coli commensal strains, for proper development of biofilm, and for virulence in some pathogens. New understanding of how the Rcs phosphorelay works provides insight into the flexibility of the two-component system paradigm.
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Affiliation(s)
- Erin Wall
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
| | - Nadim Majdalani
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
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Gialama D, Delivoria DC, Michou M, Giannakopoulou A, Skretas G. Functional Requirements for DjlA- and RraA-Mediated Enhancement of Recombinant Membrane Protein Production in the Engineered Escherichia coli Strains SuptoxD and SuptoxR. J Mol Biol 2017; 429:1800-1816. [PMID: 28501587 DOI: 10.1016/j.jmb.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 04/30/2017] [Accepted: 05/04/2017] [Indexed: 12/17/2022]
Abstract
In previous work, we have generated the engineered Escherichia coli strains SuptoxD and SuptoxR, which upon co-expression of the effector genes djlA or rraA, respectively, are capable of suppressing the cytotoxicity caused by membrane protein (MP) overexpression and of producing dramatically enhanced yields for a variety of recombinant MPs of both prokaryotic and eukaryotic origin. Here, we investigated the functional requirements for DnaJ-like protein A (DjlA)- and regulator of ribonuclease activity A (RraA)-mediated enhancement of recombinant MP production in these strains and show that: (i) DjlA and RraA act independently, that is, the beneficial effects of each protein on recombinant MP production occur through a mechanism that does not involve the other, and in a non-additive manner; (ii) full-length and membrane-bound DjlA is required for exerting its beneficial effects on recombinant MP production in E. coli SuptoxD; (iii) the MP production-promoting properties of DjlA in SuptoxD involve the action of the molecular chaperone DnaK but do not rely on the activation of the regulation of capsular synthesis response, a well-established consequence of djlA overexpression; (iv) the observed RraA-mediated effects in E. coli SuptoxR involve the ribonucleolytic activity of RNase E, but not that of its paralogous ribonuclease RNase G; and (v) DjlA and RraA are unique among similar E. coli proteins in their ability to promote bacterial recombinant MP production. These observations provide important clues about the molecular requirements for suppressed toxicity and enhanced MP accumulation in SuptoxD/SuptoxR and will guide future studies aiming to decipher the exact mechanism of DjlA- and RraA-mediated enhancement of recombinant MP production in these strains.
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Affiliation(s)
- Dimitra Gialama
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece; Laboratory of Biotechnology, School of Chemical Engineering, National Technical University of Athens, Athens, 15780, Greece
| | - Dafni Chrysanthi Delivoria
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece; Laboratory of Biotechnology, School of Chemical Engineering, National Technical University of Athens, Athens, 15780, Greece
| | - Myrsini Michou
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece; Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, 41500, Greece
| | - Artemis Giannakopoulou
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece
| | - Georgios Skretas
- Institute of Biology, Medicinal Chemistry & Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece.
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13
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Bhandari V, Houry WA. Substrate Interaction Networks of the Escherichia coli Chaperones: Trigger Factor, DnaK and GroEL. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 883:271-94. [PMID: 26621473 DOI: 10.1007/978-3-319-23603-2_15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the dense cellular environment, protein misfolding and inter-molecular protein aggregation compete with protein folding. Chaperones associate with proteins to prevent misfolding and to assist in folding to the native state. In Escherichia coli, the chaperones trigger factor, DnaK/DnaJ/GrpE, and GroEL/ES are the major chaperones responsible for insuring proper de novo protein folding. With multitudes of proteins produced by the bacterium, the chaperones have to be selective for their substrates. Yet, chaperone selectivity cannot be too specific. Recent biochemical and high-throughput studies have provided important insights highlighting the strategies used by chaperones in maintaining proteostasis in the cell. Here, we discuss the substrate networks and cooperation among these protein folding chaperones.
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Affiliation(s)
- Vaibhav Bhandari
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 5308, Toronto, ON, M5S 1A8, Canada
| | - Walid A Houry
- Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building, Room 5308, Toronto, ON, M5S 1A8, Canada.
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Chen DH, Huang Y, Liu C, Ruan Y, Shen WH. Functional conservation and divergence of J-domain-containing ZUO1/ZRF orthologs throughout evolution. PLANTA 2014; 239:1159-1173. [PMID: 24659052 DOI: 10.1007/s00425-014-2058-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/05/2014] [Indexed: 06/03/2023]
Abstract
Heat shock protein 40s (Hsp40s), also known as J-proteins, are conserved in prokaryotes and eukaryotes. The Zuotin/Zuotin-related factor (ZUO1/ZRF) family belongs to a novel Hsp40 clade exclusively found in eukaryotes. Zuotin/Zuotin-related factor proteins are characterized by a large N terminal ZUO1 domain originally identified in the yeast ZUO1 protein. The ZUO1 domain is characterized by a highly conserved J-domain, together with an atypical UBD domain first identified in the human ZRF1 protein. Furthermore, ZUO1/ZRF protein families in animals and plants harbor a pair of C terminal SANT domains, suggesting the divergence of their functions with those in fungi. Zuotin/Zuotin-related factor proteins retain the ancestral function as an Hsp70co-chaperone implicated in protein folding and renaturation after stress; these proteins also perform diverse neofunctions in the cytoplasm and transcriptional and/or epigenetic regulatory functions in the nucleus. Therefore, these proteins are involved in translational fidelity control, ribosomal biogenesis, asymmetric cell division, cell cycle, apoptosis, differentiation, and tumorigenesis. The results of sequence and domain organization analysis of proteins from diverse organisms provided valuable insights into the evolutionary conservation and diversity of ZUO1/ZRF protein family. Further, phylogenetic analysis provides a platform for future functional investigation on the ZUO1/ZRF protein family, particularly in higher plants.
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Burger A, Ludewig MH, Boshoff A. Investigating the Chaperone Properties of a Novel Heat Shock Protein, Hsp70.c, from Trypanosoma brucei. J Parasitol Res 2014; 2014:172582. [PMID: 24707395 PMCID: PMC3953656 DOI: 10.1155/2014/172582] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 12/23/2013] [Accepted: 01/09/2014] [Indexed: 02/06/2023] Open
Abstract
The neglected tropical disease, African Trypanosomiasis, is fatal and has a crippling impact on economic development. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is expressed in response to stress and Hsp40 acts as its co-chaperone. These proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. A novel cytosolic Hsp70, from Trypanosoma brucei, TbHsp70.c, contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. The ability of a cytosolic Hsp40 from Trypanosoma brucei J protein 2, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective was to functionally characterize TbHsp70.c to further expand our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed the ability to suppress aggregation of thermolabile MDH and chemically denatured rhodanese. ATPase assays revealed a 2.8-fold stimulation of the ATPase activity of TbHsp70.c by Tbj2. TbHsp70.c and Tbj2 both demonstrated chaperone activity and Tbj2 functions as a co-chaperone of TbHsp70.c. In vivo heat stress experiments indicated upregulation of the expression levels of TbHsp70.c.
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Affiliation(s)
- Adélle Burger
- Biomedical and Biotechnology Research Unit (BioBRU), Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
| | - Michael H. Ludewig
- Biomedical and Biotechnology Research Unit (BioBRU), Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
| | - Aileen Boshoff
- Biomedical and Biotechnology Research Unit (BioBRU), Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa
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16
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Velineni S, Desoutter D, Perchec AM, Timoney JF. Characterization of a mucoid clone of Streptococcus zooepidemicus from an epizootic of equine respiratory disease in New Caledonia. Vet J 2014; 200:82-7. [PMID: 24618399 DOI: 10.1016/j.tvjl.2014.01.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 01/21/2014] [Accepted: 01/23/2014] [Indexed: 11/18/2022]
Abstract
Streptococcus equi subspecies zooepidemicus (Sz) is a tonsillar and mucosal commensal of healthy horses with the potential to cause opportunistic infections of the distal respiratory tract stressed by virus infection, transportation, training or high temperature. The invasive clone varies from horse to horse with little evidence of lateral transmission in the group. Tonsillar isolates are non-mucoid although primary isolates from opportunist lower respiratory tract infections may initially be mucoid. In this study, a novel stably mucoid Sz (SzNC) from a clonal epizootic of respiratory disease in horses in different parts of New Caledonia is described. SzNC (ST-307) was isolated in pure culture from transtracheal aspirates and as heavy growths from 80% of nasal swabs (n=31). Only 4% of swabs from unaffected horses (n=25) yielded colonies of Sz. A viral etiology was ruled out based on culture and early/late serum antibody screening. Evidence for clonality of SzNC included a mucoid colony phenotype, SzP and SzM sequences, and multilocus sequence typing. SzNC, with the exception of isolates at the end of the outbreak, was hyaluronidase positive. Its SzP protein was composed of an N2 terminal, and HV4 variable region motifs and 18 carboxy terminal PEPK repeats. Biotin labeling of surface proteins revealed DnaK and alanyl-tRNA synthetase (AlaS) on the surface of clonal isolates, but not on non-clonal non-mucoid Sz from horses in the epizootic or unrelated US isolates. Reactivity of these proteins and SzP with convalescent serum indicated expression during infection.
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Affiliation(s)
- Sridhar Velineni
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA
| | - Denise Desoutter
- Laboratoire Territorial de Diagnostic Vétérinaire, BP42 Paita, New Caledonia
| | - Anne-Marie Perchec
- Laboratoire Territorial de Diagnostic Vétérinaire, BP42 Paita, New Caledonia
| | - John F Timoney
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA.
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Castanié-Cornet MP, Bruel N, Genevaux P. Chaperone networking facilitates protein targeting to the bacterial cytoplasmic membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1442-56. [PMID: 24269840 DOI: 10.1016/j.bbamcr.2013.11.007] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/10/2013] [Accepted: 11/13/2013] [Indexed: 12/22/2022]
Abstract
Nascent polypeptides emerging from the ribosome are assisted by a pool of molecular chaperones and targeting factors, which enable them to efficiently partition as cytosolic, integral membrane or exported proteins. Extensive genetic and biochemical analyses have significantly expanded our knowledge of chaperone tasking throughout this process. In bacteria, it is known that the folding of newly-synthesized cytosolic proteins is mainly orchestrated by three highly conserved molecular chaperones, namely Trigger Factor (TF), DnaK (HSP70) and GroEL (HSP60). Yet, it has been reported that these major chaperones are strongly involved in protein translocation pathways as well. This review describes such essential molecular chaperone functions, with emphasis on both the biogenesis of inner membrane proteins and the post-translational targeting of presecretory proteins to the Sec and the twin-arginine translocation (Tat) pathways. Critical interplay between TF, DnaK, GroEL and other molecular chaperones and targeting factors, including SecB, SecA, the signal recognition particle (SRP) and the redox enzyme maturation proteins (REMPs) is also discussed. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Marie-Pierre Castanié-Cornet
- Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France
| | - Nicolas Bruel
- Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France
| | - Pierre Genevaux
- Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France.
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18
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Schwizer S, Tasara T, Zurfluh K, Stephan R, Lehner A. Identification of genes involved in serum tolerance in the clinical strain Cronobacter sakazakii ES5. BMC Microbiol 2013; 13:38. [PMID: 23414256 PMCID: PMC3621496 DOI: 10.1186/1471-2180-13-38] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 02/14/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cronobacter spp. are opportunistic pathogens that can cause septicemia and infections of the central nervous system primarily in premature, low-birth weight and/or immune-compromised neonates. Serum resistance is a crucial virulence factor for the development of systemic infections, including bacteremia. It was the aim of the current study to identify genes involved in serum tolerance in a selected Cronobacter sakazakii strain of clinical origin. RESULTS Screening of 2749 random transposon knock out mutants of a C. sakazakii ES 5 library for modified serum tolerance (compared to wild type) revealed 10 mutants showing significantly increased/reduced resistance to serum killing. Identification of the affected sites in mutants displaying reduced serum resistance revealed genes encoding for surface and membrane proteins as well as regulatory elements or chaperones. By this approach, the involvement of the yet undescribed Wzy_C superfamily domain containing coding region in serum tolerance was observed and experimentally confirmed. Additionally, knock out mutants with enhanced serum tolerance were observed. Examination of respective transposon insertion loci revealed regulatory (repressor) elements, coding regions for chaperones and efflux systems as well as the coding region for the protein YbaJ. Real time expression analysis experiments revealed, that knock out of the gene for this protein negatively affects the expression of the fimA gene, which is a key structural component of the formation of fimbriae. Fimbriae are structures of high immunogenic potential and it is likely that absence/truncation of the ybaJ gene resulted in a non-fimbriated phenotype accounting for the enhanced survival of this mutant in human serum. CONCLUSION By using a transposon knock out approach we were able to identify genes involved in both increased and reduced serum tolerance in Cronobacter sakazakii ES5. This study reveals first insights in the complex nature of serum tolerance of Cronobacter spp.
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Affiliation(s)
- Sarah Schwizer
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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A bacteriophage-encoded J-domain protein interacts with the DnaK/Hsp70 chaperone and stabilizes the heat-shock factor σ32 of Escherichia coli. PLoS Genet 2012; 8:e1003037. [PMID: 23133404 PMCID: PMC3486835 DOI: 10.1371/journal.pgen.1003037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 09/04/2012] [Indexed: 01/21/2023] Open
Abstract
The universally conserved J-domain proteins (JDPs) are obligate cochaperone partners of the Hsp70 (DnaK) chaperone. They stimulate Hsp70's ATPase activity, facilitate substrate delivery, and confer specific cellular localization to Hsp70. In this work, we have identified and characterized the first functional JDP protein encoded by a bacteriophage. Specifically, we show that the ORFan gene 057w of the T4-related enterobacteriophage RB43 encodes a bona fide JDP protein, named Rki, which specifically interacts with the Escherichia coli host multifunctional DnaK chaperone. However, in sharp contrast with the three known host JDP cochaperones of DnaK encoded by E. coli, Rki does not act as a generic cochaperone in vivo or in vitro. Expression of Rki alone is highly toxic for wild-type E. coli, but toxicity is abolished in the absence of endogenous DnaK or when the conserved J-domain of Rki is mutated. Further in vivo analyses revealed that Rki is expressed early after infection by RB43 and that deletion of the rki gene significantly impairs RB43 proliferation. Furthermore, we show that mutations in the host dnaK gene efficiently suppress the growth phenotype of the RB43 rki deletion mutant, thus indicating that Rki specifically interferes with DnaK cellular function. Finally, we show that the interaction of Rki with the host DnaK chaperone rapidly results in the stabilization of the heat-shock factor σ32, which is normally targeted for degradation by DnaK. The mechanism by which the Rki-dependent stabilization of σ32 facilitates RB43 bacteriophage proliferation is discussed. Bacteriophages are the most abundant biological entities on earth. As a consequence, they represent the largest reservoir of unexplored genetic information. They control bacterial growth, mediate horizontal gene transfer, and thus exert profound influence on microbial ecology and growth. One of the striking features of bacteriophages is that they code for many open reading frames of thus far unknown biological function (called ORFans), which have been referred to as the dark matter of our biosphere. Here we have extensively characterized such a novel ORFan-encoded protein, Rki, encoded by the large, virulent enterobacteriaceae bacteriophage RB43. We show that Rki functions to control the host stress-response during the early stages of bacteriophage infection, specifically by interacting with the host DnaK/Hsp70 chaperone to stabilize the major host heat-shock factor, σ32.
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20
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Arachea BT, Sun Z, Potente N, Malik R, Isailovic D, Viola RE. Detergent selection for enhanced extraction of membrane proteins. Protein Expr Purif 2012; 86:12-20. [DOI: 10.1016/j.pep.2012.08.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 08/19/2012] [Accepted: 08/20/2012] [Indexed: 12/16/2022]
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21
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Functional analysis of the exported type IV HSP40 protein PfGECO in Plasmodium falciparum gametocytes. EUKARYOTIC CELL 2011; 10:1492-503. [PMID: 21965515 DOI: 10.1128/ec.05155-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During Plasmodium falciparum infection, host red blood cell (RBC) remodeling is required for the parasite's survival. Such modifications are mediated by the export of parasite proteins into the RBC that alter the architecture of the RBC membrane and enable cytoadherence. It is probable that some exported proteins also play a protective role against the host defense response. This may be of particular importance for the gametocyte stage of the life cycle that is responsible for malaria transmission, since the gametocyte remains in contact with blood as it proceeds through five morphological stages (I to V) during its 12-day maturation. Using microarray analysis, we identified several genes with encoded secretory or export sequences that were differentially expressed during early gametocytogenesis. One of these, PfGECO, encodes a predicted type IV heat shock protein 40 (HSP40) that we show is expressed in gametocyte stages I to IV and is exported to the RBC cytoplasm. HSPs are traditionally induced under stressful conditions to maintain homeostasis, but PfGECO expression was not increased upon heat shock, suggesting an alternate function. Targeted disruption of PfGECO indicated that the gene is not essential for gametocytogenesis in vitro, and quantitative reverse transcriptase PCR (RT-PCR) showed that there was no compensatory expression of the other type IV HSP40 genes. Although P. falciparum HSP40 members are implicated in the trafficking of proteins to the RBC surface, removal of PfGECO did not affect the targeting of other exported gametocyte proteins. This work has expanded the repertoire of known gametocyte-exported proteins to include a type IV HSP40, PfGECO.
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22
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The diverse members of the mammalian HSP70 machine show distinct chaperone-like activities. Biochem J 2011; 435:127-42. [PMID: 21231916 DOI: 10.1042/bj20101247] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Humans contain many HSP (heat-shock protein) 70/HSPA- and HSP40/DNAJ-encoding genes and most of the corresponding proteins are localized in the cytosol. To test for possible functional differences and/or substrate specificity, we assessed the effect of overexpression of each of these HSPs on refolding of heat-denatured luciferase and on the suppression of aggregation of a non-foldable polyQ (polyglutamine)-expanded Huntingtin fragment. Overexpressed chaperones that suppressed polyQ aggregation were found not to be able to stimulate luciferase refolding. Inversely, chaperones that supported luciferase refolding were poor suppressors of polyQ aggregation. This was not related to client specificity itself, as the polyQ aggregation inhibitors often also suppressed heat-induced aggregation of luciferase. Surprisingly, the exclusively heat-inducible HSPA6 lacks both luciferase refolding and polyQ aggregation-suppressing activities. Furthermore, whereas overexpression of HSPA1A protected cells from heat-induced cell death, overexpression of HSPA6 did not. Inversely, siRNA (small interfering RNA)-mediated blocking of HSPA6 did not impair the development of heat-induced thermotolerance. Yet, HSPA6 has a functional substrate-binding domain and possesses intrinsic ATPase activity that is as high as that of the canonical HSPA1A when stimulated by J-proteins. In vitro data suggest that this may be relevant to substrate specificity, as purified HSPA6 could not chaperone heat-unfolded luciferase but was able to assist in reactivation of heat-unfolded p53. So, even within the highly sequence-conserved HSPA family, functional differentiation is larger than expected, with HSPA6 being an extreme example that may have evolved to maintain specific critical functions under conditions of severe stress.
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23
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Sabate R, de Groot NS, Ventura S. Protein folding and aggregation in bacteria. Cell Mol Life Sci 2010; 67:2695-715. [PMID: 20358253 PMCID: PMC11115605 DOI: 10.1007/s00018-010-0344-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 02/19/2010] [Accepted: 03/05/2010] [Indexed: 01/31/2023]
Abstract
Proteins might experience many conformational changes and interactions during their lifetimes, from their synthesis at ribosomes to their controlled degradation. Because, in most cases, only folded proteins are functional, protein folding in bacteria is tightly controlled genetically, transcriptionally, and at the protein sequence level. In addition, important cellular machinery assists the folding of polypeptides to avoid misfolding and ensure the attainment of functional structures. When these redundant protective strategies are overcome, misfolded polypeptides are recruited into insoluble inclusion bodies. The protein embedded in these intracellular deposits might display different conformations including functional and beta-sheet-rich structures. The latter assemblies are similar to the amyloid fibrils characteristic of several human neurodegenerative diseases. Interestingly, bacteria exploit the same structural principles for functional properties such as adhesion or cytotoxicity. Overall, this review illustrates how prokaryotic organisms might provide the bedrock on which to understand the complexity of protein folding and aggregation in the cell.
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Affiliation(s)
- Raimon Sabate
- Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Natalia S. de Groot
- Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
| | - Salvador Ventura
- Departament de Bioquímica i Biologia Molecular, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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24
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Chen Z, Xu X. DnaJ-like protein gene sll1384 is involved in phototaxis in Synechocystis sp. PCC 6803. Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-009-0674-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Louw CA, Ludewig MH, Blatch GL. Overproduction, purification and characterisation of Tbj1, a novel Type III Hsp40 from Trypanosoma brucei, the African sleeping sickness parasite. Protein Expr Purif 2009; 69:168-77. [PMID: 19815073 DOI: 10.1016/j.pep.2009.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/27/2009] [Accepted: 09/29/2009] [Indexed: 11/24/2022]
Abstract
The heat shock protein 40 (Hsp40) family of proteins act as co-chaperones of the heat shock protein 70 (Hsp70) chaperone family, and together they play a vital role in the maintenance of cellular homeostasis. The Type III class of Hsp40s are diverse in terms of both sequence identity and function and have not been extensively characterised. The Trypanosoma brucei parasite is the causative agent of Human African Trypanosomiasis, and possesses an unusually large Hsp40 complement, consisting mostly of Type III Hsp40s. A novel T. brucei Type III Hsp40, Tbj1, was heterologously expressed, purified, and found to exist as a compact monomer in solution. Using polyclonal antibodies to the full-length recombinant protein, Tbj1 was found by Western analysis to be expressed in the T. brucei bloodstream-form. Tbj1 was found to be able to assist two different Hsp70 proteins in the suppression of protein aggregation in vitro, despite being unable to stimulate their ATPase activity. This indicated that while Tbj1 did not possess independent chaperone activity, it potentially functioned as a novel co-chaperone of Hsp70 in T. brucei.
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Affiliation(s)
- Cassandra A Louw
- Biomedical Biotechnology Research Unit, Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
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26
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Lakhal F, Bury-Moné S, Nomane Y, Le Goïc N, Paillard C, Jacq A. DjlA, a membrane-anchored DnaJ-like protein, is required for cytotoxicity of clam pathogen Vibrio tapetis to hemocytes. Appl Environ Microbiol 2008; 74:5750-8. [PMID: 18641167 PMCID: PMC2547034 DOI: 10.1128/aem.01043-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
DjlA is an inner membrane cochaperone belonging to the DnaJ family, which has been shown to be involved in Legionella sp. pathogenesis. In this study, we explored the role of this protein in the physiology and virulence of Vibrio tapetis, the etiological agent of brown ring disease (BRD) in Manila clam (Ruditapes philippinarum). Analysis of the djlA locus in V. tapetis revealed a putative organization in an operon with a downstream gene that we designated duf924(Vt), which encodes a conserved protein with an unknown function and has homologues in bacteria and eukaryotes. djlA mutants displayed a reduced growth rate and showed an important loss of cytotoxic activity against R. philippinarum hemocytes in vitro, which could be restored by extrachromosomal expression of wild-type djlA(Vt) but not duf924(Vt). These results are in keeping with the potential importance of DjlA for bacterial pathogenicity and open new perspectives for understanding the mechanism of action of this protein in the novel V. tapetis-R. philippinarum interaction model.
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Affiliation(s)
- Fatma Lakhal
- Institut de Génétique et Microbiologie, Bâtiment 400, Université Paris-Sud, Orsay 91405 Cedex, France
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The Plasmodium falciparum heat shock protein 40, Pfj4, associates with heat shock protein 70 and shows similar heat induction and localisation patterns. Int J Biochem Cell Biol 2008; 40:2914-26. [PMID: 18674634 DOI: 10.1016/j.biocel.2008.06.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 06/24/2008] [Accepted: 06/25/2008] [Indexed: 11/24/2022]
Abstract
Human cerebral malaria is caused by the protozoan parasite Plasmodium falciparum, which establishes itself within erythrocytes. The normal body temperature in the human host could constitute a possible source of heat stress to the parasite. Molecular chaperones belonging to the heat shock protein (Hsp) class are thought to be important for parasite subsistence in the host cell, as the expression of some members of this family has been reported to increase upon heat shock. In this paper we investigated the possible functions of the P. falciparum heat shock protein DnaJ homologue Pfj4, a type II Hsp40 protein. We analysed the ability of Pfj4 to functionally replace Escherichia coli Hsp40 proteins in a dnaJ cbpA mutant strain. Western analysis on cellular fractions of P. falciparum-infected erythrocytes revealed that Pfj4 expression increased upon heat shock. Localisation studies using immunofluorescence and immuno-electron microscopy suggested that Pfj4 and P. falciparum Hsp70, PfHsp70-1, were both localised to the parasites nucleus and cytoplasm. In some cases, Pfj4 was also detected in the erythrocyte cytoplasm of infected erythrocytes. Immunoprecipitation studies and size exclusion chromatography indicated that Pfj4 and PfHsp70-1 may directly or indirectly interact. Our results suggest a possible involvement of Pfj4 together with PfHsp70-1 in cytoprotection, and therefore, parasite survival inside the erythrocyte.
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28
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Zhang XS, García-Contreras R, Wood TK. Escherichia coli transcription factor YncC (McbR) regulates colanic acid and biofilm formation by repressing expression of periplasmic protein YbiM (McbA). ISME JOURNAL 2008; 2:615-31. [PMID: 18309357 DOI: 10.1038/ismej.2008.24] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Quorum-sensing signal autoinducer 2 (AI-2) stimulates Escherichia coli biofilm formation through the motility regulator MqsR that induces expression of the putative transcription factor encoded by yncC. Here, we show that YncC increases biofilm formation by repressing overproduction of the exopolysaccharide identified as colanic acid (corroborated by decreasing mucoidy and increased sensitivity to bacteriophage P1 infection). Differential gene expression and gel shift assays demonstrated that YncC is a repressor of the predicted periplasmic protein-encoding gene, ybiM, which was corroborated by the isogenic yncC ybiM double mutation that repressed the yncC phenotypes (biofilm formation, colanic acid overproduction, mucoidy and bacteriophage resistance). Through nickel-enrichment DNA microarrays and additional gel shift assays, we found that the putative transcription factor B3023 (directly upstream of mqsR) binds the yncC promoter. Overexpressing MqsR, AI-2 import regulators LsrR/LsrK and AI-2 exporter TqsA induced yncC transcription, whereas the AI-2 synthase LuxS and B3023 repressed yncC. MqsR has a toxic effect on E. coli bacterial growth, which is partially reduced by the b3023 mutation. Therefore, AI-2 quorum-sensing control of biofilm formation is mediated through regulator MqsR that induces expression of the transcription factor YncC. YncC inhibits the expression of periplasmic YbiM, which prevents overproduction of colanic acid (excess colanic acid causes mucoidy) and prevents YbiM from inhibiting biofilm formation.
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Affiliation(s)
- Xue-Song Zhang
- Artie McFerrin Department of Chemical Engineering, Texas A & M University, College Station, TX 77843-3122, USA
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29
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Shiba Y, Matsumoto K, Hara H. DjlA negatively regulates the Rcs signal transduction system in Escherichia coli. Genes Genet Syst 2007; 81:51-6. [PMID: 16607041 DOI: 10.1266/ggs.81.51] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Rcs signal transduction system of Escherichia coli regulating capsular polysaccharide synthesis (cps) genes is activated by overexpression of the djlA gene encoding a cytoplasmic membrane-anchored DnaJ-like protein. However, by monitoring the expression of a cpsB'-lac fusion in pgsA- and mdoH-null mutants in which the Rcs system is activated, we found that the Rcs activity was further increased by deletion of djlA and decreased by low-level extrachromosomal expression of djlA. Furthermore, deletion of djlA in a wild-type strain led to small but significant increase of the basal-level activity of the Rcs system. These results demonstrate that DjlA functions as a negative regulator of the Rcs system unless abnormally overproduced.
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Affiliation(s)
- Yasuhiro Shiba
- Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, Japan
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Genevaux P, Georgopoulos C, Kelley WL. The Hsp70 chaperone machines of Escherichia coli: a paradigm for the repartition of chaperone functions. Mol Microbiol 2007; 66:840-57. [PMID: 17919282 DOI: 10.1111/j.1365-2958.2007.05961.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular chaperones are highly conserved in all free-living organisms. There are many types of chaperones, and most are conveniently grouped into families. Genome sequencing has revealed that many organisms contain multiple members of both the DnaK (Hsp70) family and their partner J-domain protein (JDP) cochaperone, belonging to the DnaJ (Hsp40) family. Escherichia coli K-12 encodes three Hsp70 genes and six JDP genes. The coexistence of these chaperones in the same cytosol suggests that certain chaperone-cochaperone interactions are permitted, and that chaperone tasks and their regulation have become specialized over the course of evolution. Extensive genetic and biochemical analyses have greatly expanded knowledge of chaperone tasking in this organism. In particular, recent advances in structure determination have led to significant insights of the underlying complexities and functional elegance of the Hsp70 chaperone machine.
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Affiliation(s)
- Pierre Genevaux
- Laboratoire de Microbiologie et Génétique Moléculaire, IBCG, CNRS Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, Cedex 09, France.
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31
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Nicoll W, Botha M, McNamara C, Schlange M, Pesce ER, Boshoff A, Ludewig M, Zimmermann R, Cheetham M, Chapple J, Blatch G. Cytosolic and ER J-domains of mammalian and parasitic origin can functionally interact with DnaK. Int J Biochem Cell Biol 2006; 39:736-51. [PMID: 17239655 PMCID: PMC1906734 DOI: 10.1016/j.biocel.2006.11.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 11/12/2006] [Accepted: 11/14/2006] [Indexed: 02/05/2023]
Abstract
Both prokaryotic and eukaryotic cells contain multiple heat shock protein 40 (Hsp40) and heat shock protein 70 (Hsp70) proteins, which cooperate as molecular chaperones to ensure fidelity at all stages of protein biogenesis. The Hsp40 signature domain, the J-domain, is required for binding of an Hsp40 to a partner Hsp70, and may also play a role in the specificity of the association. Through the creation of chimeric Hsp40 proteins by the replacement of the J-domain of a prokaryotic Hsp40 (DnaJ), we have tested the functional equivalence of J-domains from a number of divergent Hsp40s of mammalian and parasitic origin (malarial Pfj1 and Pfj4, trypanosomal Tcj3, human ERj3, ERj5, and Hsj1, and murine ERj1). An in vivo functional assay was used to test the functionality of the chimeric proteins on the basis of their ability to reverse the thermosensitivity of a dnaJ cbpA mutant Escherichia coli strain (OD259). The Hsp40 chimeras containing J-domains originating from soluble (cytosolic or endoplasmic reticulum (ER)-lumenal) Hsp40s were able to reverse the thermosensitivity of E. coli OD259. In all cases, modified derivatives of these chimeric proteins containing an His to Gln substitution in the HPD motif of the J-domain were unable to reverse the thermosensitivity of E. coli OD259. This suggested that these J-domains exerted their in vivo functionality through a specific interaction with E. coli Hsp70, DnaK. Interestingly, a Hsp40 chimera containing the J-domain of ERj1, an integral membrane-bound ER Hsp40, was unable to reverse the thermosensitivity of E. coli OD259, suggesting that this J-domain was unable to functionally interact with DnaK. Substitutions of conserved amino acid residues and motifs were made in all four helices (I–IV) and the loop regions of the J-domains, and the modified chimeric Hsp40s were tested for functionality using the in vivo assay. Substitution of a highly conserved basic residue in helix II of the J-domain was found to disrupt in vivo functionality for all the J-domains tested. We propose that helix II and the HPD motif of the J-domain represent the fundamental elements of a binding surface required for the interaction of Hsp40s with Hsp70s, and that this surface has been conserved in mammalian, parasitic and bacterial systems.
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Affiliation(s)
- W.S. Nicoll
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - M. Botha
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - C. McNamara
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - M. Schlange
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - E.-R. Pesce
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - A. Boshoff
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - M.H. Ludewig
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
| | - R. Zimmermann
- Department of Medical Biochemistry & Molecular Biology, Universität des Saarlandes, Homburg D66421, Germany
| | - M.E. Cheetham
- Division of Molecular and Cellular Neuroscience, Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - J.P. Chapple
- Center for Endocrinology, William Harvey Research Institute, Barts and the London, Queen Mary University of London, London C1M 6BQ, UK
| | - G.L. Blatch
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
- Corresponding author. Tel.: +27 46 603 8262; fax: +27 46 622 3984.
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Cajo GC, Horne BE, Kelley WL, Schwager F, Georgopoulos C, Genevaux P. The role of the DIF motif of the DnaJ (Hsp40) co-chaperone in the regulation of the DnaK (Hsp70) chaperone cycle. J Biol Chem 2006; 281:12436-44. [PMID: 16533811 DOI: 10.1074/jbc.m511192200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To perform effectively as a molecular chaperone, DnaK (Hsp70) necessitates the assistance of its DnaJ (Hsp40) co-chaperone partner, which efficiently stimulates its intrinsically weak ATPase activity and facilitates its interaction with polypeptide substrates. In this study, we address the function of the conserved glycine- and phenylalanine-rich (G/F-rich) region of the Escherichia coli DnaJ in the DnaK chaperone cycle. We show that the G/F-rich region is critical for DnaJ co-chaperone functions in vivo and that despite a significant degree of sequence conservation among the G/F-rich regions of Hsp40 homologs from bacteria, yeast, or humans, functional complementation in the context of the E. coli DnaJ is limited. Furthermore, we found that the deletion of the whole G/F-rich region is mirrored by mutations in the conserved Asp-Ile/Val-Phe (DIF) motif contained in this region. Further genetic and biochemical analyses revealed that this amino acid triplet plays a critical role in regulation of the DnaK chaperone cycle, possibly by modulating a crucial step subsequent to DnaK-mediated ATP hydrolysis.
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Affiliation(s)
- Gordana Cogelja Cajo
- Département de Microbiologie et Médecine Moléculaire, Centre Médical Universitaire, 1, rue Michel-Servet, CH-1211, Geneva, Switzerland
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Abstract
RcsC, RcsB, and RcsA were first identified as a sensor kinase, a response regulator, and an auxiliary regulatory protein, respectively, regulating the genes of capsular polysaccharide synthesis. Recent advances have demonstrated that these proteins are part of a complex phosphorelay, in which phosphate travels from the histidine kinase domain in RcsC to a response regulator domain in the same protein; from there to a phosphotransfer protein, RcsD; and from there to RcsB. In addition to capsule synthesis, which requires the unstable regulatory protein RcsA, RcsB also stimulates transcription of a small RNA, RprA; the cell division gene ftsZ; and genes encoding membrane and periplasmic proteins, including the osmotically inducible genes osmB and osmC. The Rcs system appears to play an important role in the later stages of biofilm development; induction of Rcs signaling by surfaces is consistent with this role.
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Affiliation(s)
- Nadim Majdalani
- Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892, USA
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34
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Cheng Q, Pappas V, Hallmann A, Miller SM. Hsp70A and GlsA interact as partner chaperones to regulate asymmetric division in Volvox. Dev Biol 2005; 286:537-48. [PMID: 16168403 DOI: 10.1016/j.ydbio.2005.08.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 08/15/2005] [Accepted: 08/16/2005] [Indexed: 11/26/2022]
Abstract
GlsA, a J-protein chaperone, is required for the asymmetric divisions that set aside germ and somatic cell precursors during embryogenesis in Volvox carteri, and previous evidence indicated that this function requires an intact Hsp70-binding site. To determine if Hsp70A, the only known cytoplasmic Hsp70 in V. carteri, is the chaperone partner of GlsA, we investigated the localization of the two proteins during critical stages of embryogenesis and tested their capacity to interact. We found that a substantial fraction of Hsp70A co-localizes with GlsA, both in interphase and mitotic blastomeres. In addition, Hsp70A coimmunoprecipitated with GlsA, and co-expression of GlsA and Hsp70A variants partially rescued the Gls phenotype of a glsA mutant, whereas neither variant by itself rescued the mutant phenotype. Immunofluorescence analysis demonstrated that GlsA is about equally abundant in all blastomeres at all cleavage stages examined but that Hsp70A is more abundant in anterior (asymmetrically dividing) blastomeres than in posterior (symmetrically dividing) blastomeres during the period of asymmetric division. We conclude that Hsp70A and GlsA function as chaperone partners that regulate asymmetric division and that the relative abundance of Hsp70A in asymmetrically dividing embryos may determine which blastomeres divide asymmetrically and which do not.
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Affiliation(s)
- Qian Cheng
- Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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35
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Hennessy F, Nicoll WS, Zimmermann R, Cheetham ME, Blatch GL. Not all J domains are created equal: implications for the specificity of Hsp40-Hsp70 interactions. Protein Sci 2005; 14:1697-709. [PMID: 15987899 PMCID: PMC2253343 DOI: 10.1110/ps.051406805] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Heat shock protein 40s (Hsp40s) and heat shock protein 70s (Hsp70s) form chaperone partnerships that are key components of cellular chaperone networks involved in facilitating the correct folding of a broad range of client proteins. While the Hsp40 family of proteins is highly diverse with multiple forms occurring in any particular cell or compartment, all its members are characterized by a J domain that directs their interaction with a partner Hsp70. Specific Hsp40-Hsp70 chaperone partnerships have been identified that are dedicated to the correct folding of distinct subsets of client proteins. The elucidation of the mechanism by which these specific Hsp40-Hsp70 partnerships are formed will greatly enhance our understanding of the way in which chaperone pathways are integrated into finely regulated protein folding networks. From in silico analyses, domain swapping and rational protein engineering experiments, evidence has accumulated that indicates that J domains contain key specificity determinants. This review will critically discuss the current understanding of the structural features of J domains that determine the specificity of interaction between Hsp40 proteins and their partner Hsp70s. We also propose a model in which the J domain is able to integrate specificity and chaperone activity.
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Affiliation(s)
- Fritha Hennessy
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa
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36
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Nicoll WS, Boshoff A, Ludewig MH, Hennessy F, Jung M, Blatch GL. Approaches to the isolation and characterization of molecular chaperones. Protein Expr Purif 2005; 46:1-15. [PMID: 16199180 DOI: 10.1016/j.pep.2005.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 08/02/2005] [Accepted: 08/04/2005] [Indexed: 10/25/2022]
Abstract
Molecular chaperones are integral components of the cellular machinery involved in ensuring correct protein folding and the continued maintenance of protein structure. An understanding of these ubiquitous molecules is key to finding cures to protein misfolding diseases such as Alzheimer's and Creutzfeldt-Jacob diseases. In addition, further understanding of chaperones will enhance our comprehension of the way the body copes with the environmental stresses that humans encounter daily. Our laboratory and our collaborators specialize in the production and characterization of chaperones from a wide variety of sources in order to gain a fuller understanding of how chaperones function in the cell. In this review, we primarily use the Hsp70/Hsp40 chaperone pair as an example to discuss recent advances in technology and reductions in cost that lend themselves to chaperone purification from both native and recombinant sources. Common assays to assess purified chaperone activity are also discussed.
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Affiliation(s)
- William S Nicoll
- Chaperone Research Group, Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown, South Africa
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37
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Hennessy F, Boshoff A, Blatch GL. Rational mutagenesis of a 40 kDa heat shock protein from Agrobacterium tumefaciens identifies amino acid residues critical to its in vivo function. Int J Biochem Cell Biol 2005; 37:177-91. [PMID: 15381160 DOI: 10.1016/j.biocel.2004.06.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2004] [Revised: 04/16/2004] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
Abstract
Prokaryotic DnaJ and DnaK, homologous to the eukaryotic 40 and 70kDa heat shock proteins (Hsp40 and Hsp70) respectively, play an important role as molecular chaperones in assisted protein folding under both normal and stressed conditions. DnaJ-like proteins are defined by the presence of a 70 amino acid domain termed the J domain, similar to the initial 73 amino acids of the Escherichia coli protein DnaJ. The J domain comprises four alpha-helices and a loop region containing the invariant tripeptide of histidine, proline and aspartic acid (HPD motif). This motif and Helix II have been shown previously to be important for the interaction with partner Hsp70s. Conserved amino acid residues present in the J domain were identified, and substitutions of these residues were performed to examine their effect on the in vivo functioning of the J domain of Agrobacterium tumefaciens DnaJ. Three conserved, charged residues, and three conserved, hydrophobic residues, in addition to the HPD motif, were shown to be important for the correct functioning of A. tumefaciens DnaJ. These included Arg26 located on Helix II, Arg63 and Asp59 located on Helix IV, Tyr7 and Leu10 located on Helix I, and Leu57 located on Helix III. This study has identified charged and hydrophobic residues on all the structural elements of the J domain that were critical to the structure and function of DnaJ, and in particular shown that Helix IV may have an important role in the structure and function of DnaJs in general.
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Affiliation(s)
- Fritha Hennessy
- Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa
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38
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Gur E, Biran D, Shechter N, Genevaux P, Georgopoulos C, Ron EZ. The Escherichia coli DjlA and CbpA proteins can substitute for DnaJ in DnaK-mediated protein disaggregation. J Bacteriol 2004; 186:7236-42. [PMID: 15489435 PMCID: PMC523209 DOI: 10.1128/jb.186.21.7236-7242.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The DnaJ (Hsp40) protein of Escherichia coli serves as a cochaperone of DnaK (Hsp70), whose activity is involved in protein folding, protein targeting for degradation, and rescue of proteins from aggregates. Two other E. coli proteins, CbpA and DjlA, which exhibit homology with DnaJ, are known to interact with DnaK and to stimulate its chaperone activity. Although it has been shown that in dnaJ mutants both CbpA and DjlA are essential for growth at temperatures above 37 degrees C, their in vivo role is poorly understood. Here we show that in a dnaJ mutant both CbpA and DjlA are required for efficient protein dissaggregation at 42 degrees C.
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Affiliation(s)
- Eyal Gur
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
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39
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Ward N, Larsen Ø, Sakwa J, Bruseth L, Khouri H, Durkin AS, Dimitrov G, Jiang L, Scanlan D, Kang KH, Lewis M, Nelson KE, Methé B, Wu M, Heidelberg JF, Paulsen IT, Fouts D, Ravel J, Tettelin H, Ren Q, Read T, DeBoy RT, Seshadri R, Salzberg SL, Jensen HB, Birkeland NK, Nelson WC, Dodson RJ, Grindhaug SH, Holt I, Eidhammer I, Jonasen I, Vanaken S, Utterback T, Feldblyum TV, Fraser CM, Lillehaug JR, Eisen JA. Genomic insights into methanotrophy: the complete genome sequence of Methylococcus capsulatus (Bath). PLoS Biol 2004; 2:e303. [PMID: 15383840 PMCID: PMC517821 DOI: 10.1371/journal.pbio.0020303] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Accepted: 07/14/2004] [Indexed: 11/23/2022] Open
Abstract
Methanotrophs are ubiquitous bacteria that can use the greenhouse gas methane as a sole carbon and energy source for growth, thus playing major roles in global carbon cycles, and in particular, substantially reducing emissions of biologically generated methane to the atmosphere. Despite their importance, and in contrast to organisms that play roles in other major parts of the carbon cycle such as photosynthesis, no genome-level studies have been published on the biology of methanotrophs. We report the first complete genome sequence to our knowledge from an obligate methanotroph, Methylococcus capsulatus (Bath), obtained by the shotgun sequencing approach. Analysis revealed a 3.3-Mb genome highly specialized for a methanotrophic lifestyle, including redundant pathways predicted to be involved in methanotrophy and duplicated genes for essential enzymes such as the methane monooxygenases. We used phylogenomic analysis, gene order information, and comparative analysis with the partially sequenced methylotroph Methylobacterium extorquens to detect genes of unknown function likely to be involved in methanotrophy and methylotrophy. Genome analysis suggests the ability of M. capsulatus to scavenge copper (including a previously unreported nonribosomal peptide synthetase) and to use copper in regulation of methanotrophy, but the exact regulatory mechanisms remain unclear. One of the most surprising outcomes of the project is evidence suggesting the existence of previously unsuspected metabolic flexibility in M. capsulatus, including an ability to grow on sugars, oxidize chemolithotrophic hydrogen and sulfur, and live under reduced oxygen tension, all of which have implications for methanotroph ecology. The availability of the complete genome of M. capsulatus (Bath) deepens our understanding of methanotroph biology and its relationship to global carbon cycles. We have gained evidence for greater metabolic flexibility than was previously known, and for genetic components that may have biotechnological potential.
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Affiliation(s)
- Naomi Ward
- The Institute for Genomic Research, Rockville, Maryland, USA.
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40
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Domínguez-Bernal G, Pucciarelli MG, Ramos-Morales F, García-Quintanilla M, Cano DA, Casadesús J, García-del Portillo F. Repression of the RcsC-YojN-RcsB phosphorelay by the IgaA protein is a requisite for Salmonella virulence. Mol Microbiol 2004; 53:1437-49. [PMID: 15387821 DOI: 10.1111/j.1365-2958.2004.04213.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Bacterial pathogenesis relies on regulators that activate virulence genes. Some of them act, in addition, as repressors of specific genes. Intracellular-growth-attenuator-A (IgaA) is a Salmonella enterica membrane protein that prevents overactivation of the RcsC-YojN-RcsB regulatory system. This negative control is critical for growth because disruption of the igaA gene is only possible in rcsC, yojN or rcsB strains. In this work, we examined the contribution of this regulatory circuit to virulence. Viable igaA point mutant alleles were isolated and characterized. These alleles encode IgaA variants leading to different levels of activation of the RcsC-YojN-RcsB system. IgaA-mediated repression of the RcsB-YojN-RcsC system occurred at the post-translational level, as shown by chromosomal epitope tagging of the rcsC, yojN and rcsB genes. The activity of the RcsC-YojN-RcsB system, monitored with the product of a tagged gmd-3xFLAG gene (positively regulated by RcsC-YojN-RcsB), was totally abolished by wild-type bacteria in mouse target organs. Such tight repression occurred only in vivo and was mediated by IgaA. Shutdown of the RcsC-YojN-RcsB system is a requisite for Salmonella virulence since all igaA point mutant strains were highly attenuated. The degree of attenuation correlated to that of the activation status of RcsC-YojN-RcsB. In some cases, the attenuation recorded was unprecedented, with competitive index (CI) values as low as 10(-6). Strikingly, IgaA is a protein absolutely dispensable for virulence in mutant strains having a non-functional RcsC-YojN-RcsB system. To our knowledge, IgaA exemplifies the first protein that contributes to virulence by exclusively acting as a negative regulator upon host colonization.
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Affiliation(s)
- Gustavo Domínguez-Bernal
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain
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41
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Ohnishi H, Mizunoe Y, Takade A, Tanaka Y, Miyamoto H, Harada M, Yoshida SI. Legionella dumoffii DjlA, a member of the DnaJ family, is required for intracellular growth. Infect Immun 2004; 72:3592-603. [PMID: 15155669 PMCID: PMC415686 DOI: 10.1128/iai.72.6.3592-3603.2004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Legionella dumoffii is one of the common causes of Legionnaires' disease and is capable of replicating in macrophages. To understand the mechanism of survival within macrophages, transposon mutagenesis was employed to isolate the genes necessary for intracellular growth. We identified four defective mutants after screening 790 transposon insertion mutants. Two transposon insertions were in genes homologous to icmB or dotC, within dot/icm loci, required for intracellular multiplication of L. pneumophila. The third was in a gene whose product is homologous to the 17-kDa antigen forming part of the VirB/VirD4 type IV secretion system of Bartonella henselae. The fourth was in the djlA (for "dnaj-like A") gene. DjlA is a member of the DnaJ/Hsp40 family. Transcomplementation of the djlA mutant restored the parental phenotype in J774 macrophages, A549 human alveolar epithelial cells, and the amoeba Acanthamoeba culbertsoni. Using confocal laser-scanning microscopy and transmission electron microscopy, we revealed that in contrast to the wild-type strain, L. dumoffii djlA mutant-containing phagosomes were unable to inhibit phagosome-lysosome fusion. Transmission electron microscopy also showed that in contrast to the virulent parental strain, the djlA mutant was not able to recruit host cell rough endoplasmic reticulum. Furthermore, the stationary-phase L. dumoffii djlA mutants were more susceptible to H2O2, high osmolarity, high temperature, and low pH than was their parental strain. These results indicate that DjlA is required for intracellular growth and organelle trafficking, as well as bacterial resistance to environmental stress. This is the first report demonstrating that a single DjlA-deficient mutant exhibits a distinct phenotype.
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Affiliation(s)
- Hiroko Ohnishi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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42
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Arifuzzaman M, Oshima T, Mori H. The ATPase domain of HscC (DnaK homolog) is essential for interfering sigma70 activity in E. coli. FEMS Microbiol Lett 2004; 230:99-104. [PMID: 14734171 DOI: 10.1016/s0378-1097(03)00863-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
HscC, a DnaK homolog in Escherichia coli, consists of adenosine triphosphatase (ATPase), substrate-binding and C-terminal domains. Overexpression of HscC markedly inhibits growth of host cell and reduces the sigma(70)-dependent promoter activity presumably by forming a complex with sigma(70). To identify the region(s) of HscC responsible for growth inhibition and complex formation with sigma(70), domain swapping experiments were carried out between DnaK and HscC. Thus the chimeric proteins carrying the ATPase domain of HscC and substrate-binding domains of either HscC or DnaK were found to inhibit the growth of the cell, reduce the sigma(70)-dependent promoter activity and form a complex with sigma(70). These results indicate that the ATPase domain of HscC rather than the substrate-binding domain is important for determining its functional specificity.
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Affiliation(s)
- Mohammad Arifuzzaman
- Department of Cell Biology, NARA Institute of Science and Technology, Ikoma, Japan
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43
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Genevaux P, Lang F, Schwager F, Vartikar JV, Rundell K, Pipas JM, Georgopoulos C, Kelley WL. Simian virus 40 T antigens and J domains: analysis of Hsp40 cochaperone functions in Escherichia coli. J Virol 2003; 77:10706-13. [PMID: 12970459 PMCID: PMC228479 DOI: 10.1128/jvi.77.19.10706-10713.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The N-terminal exon of DNA tumor virus T antigens represents a J domain that can direct interaction with the host-encoded Hsp70 chaperones. We have taken advantage of rapid Hsp40 cochaperone assays with Escherichia coli to assess simian virus 40 (SV40)-encoded J-domain loss of function. We found a strong correlation between loss of cochaperone function in E. coli and defective SV40 growth, suggesting that the major role of the J domain in DNA tumor viruses is to provide cochaperone function. We also report the expression of native SV40 virus T antigens in E. coli. Our results show that small t antigen, but not large T antigen (LT) or LT truncation TN125 or TN136, can functionally replace under limited growth conditions DnaJ (Hsp40) function in vivo. In addition, purified small t antigen can efficiently stimulate E. coli DnaK's (Hsp70) ATPase in vitro, thus behaving like a bona fide cochaperone. Furthermore, small t amino acids 83 to 174, which are adjacent to the viral J domain, can replace the E. coli DnaJ J-domain glycine-phenylalanine-rich domain, immediately adjacent to the J-domain sequences, even in the absence of significant amino acid similarity to their DnaJ counterpart. Taken together, our studies demonstrate that functionally related Hsp40 proteins from mammalian viral systems can be rapidly studied in bacteria and exploited to probe the universally conserved Hsp70 chaperone machine mechanism.
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Affiliation(s)
- Pierre Genevaux
- Département de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, CH-1211 Genève 14, Switzerland
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44
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Mouslim C, Latifi T, Groisman EA. Signal-dependent requirement for the co-activator protein RcsA in transcription of the RcsB-regulated ugd gene. J Biol Chem 2003; 278:50588-95. [PMID: 14514676 DOI: 10.1074/jbc.m309433200] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The RcsC/YojN/RcsB phosphorelay system controls gene expression in response to a variety of signals, including changes in temperature, osmolarity, and overproduction of membrane proteins. Transcription of certain RcsB-activated genes, such as the capsule synthesis cps operon, requires the co-activator protein RcsA, whereas expression of other RcsB-activated genes is RcsA-independent. We have established previously that a tolB mutation induces transcription of the Salmonella UDP-glucose dehydrogenase ugd gene in an RcsA- and RcsB-dependent manner. This induction is independent of the two-component systems PhoP/PhoQ and PmrA/PmrB, which are required for ugd expression in response to low Mg2+. We now report that the RcsC/YojN/RcsB system is activated in a pmrA mutant experiencing Fe3+ and low Mg2+, resulting in expression of both cps and ugd genes. However, whereas cps transcription remained RcsA-dependent, ugd transcription became RcsA-independent but dependent on the PhoP protein. S1 mapping experiments demonstrated that RcsA-dependent and -independent transcription of the ugd gene use the same promoter. DNase footprinting analysis identified a PhoP-binding site in the ugd promoter. Yet, PhoP-mediated ugd transcription required either the RcsC/YojN/RcsB or the PmrA/PmrB systems.
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Affiliation(s)
- Chakib Mouslim
- Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Varvasovszki V, Glatz A, Shigapova N, Jósvay K, Vígh L, Horváth I. Only one dnaK homolog, dnaK2, is active transcriptionally and is essential in Synechocystis. Biochem Biophys Res Commun 2003; 305:641-8. [PMID: 12763042 DOI: 10.1016/s0006-291x(03)00822-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the expression and the function of the DnaK chaperone family in the photoautotrophic cyanobacterium, Synechocystis PCC 6803. Surprisingly, only one of the three dnaK genes was transcribed either under normal or heat shock conditions. Their predicted cochaperones (four dnaJs and one grpE) proved to be uninducible under our experimental conditions. Attempts to inactivate the active dnaK2 has failed, indicating that the gene is essential. The partial mutant displayed lower inducibility of chaperones (especially GroEL and HSP17) both at mRNA and protein levels upon heat shock. The mutant showed temperature sensitive phenotype, but was able to acquire thermotolerance.
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Affiliation(s)
- Viktória Varvasovszki
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary
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46
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Han W, Christen P. Mechanism of the targeting action of DnaJ in the DnaK molecular chaperone system. J Biol Chem 2003; 278:19038-43. [PMID: 12654915 DOI: 10.1074/jbc.m300756200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the DnaK (Hsp70) molecular chaperone system of Escherichia coli, the substrate polypeptide is fed into the chaperone cycle by association with the fast-binding, ATP-liganded form of the DnaK. The substrate binding properties of DnaK are controlled by its two cochaperones DnaJ (Hsp40) and GrpE. DnaJ stimulates the hydrolysis of DnaK-bound ATP, and GrpE accelerates ADP/ATP exchange. DnaJ has been described as targeting the substrate to DnaK, a concept that has remained rather obscure. Based on binding experiments with peptides and polypeptides we propose here a novel mechanism for the targeting action of DnaJ: ATP.DnaK and DnaJ with its substrate-binding domain bind to different segments of one and the same polypeptide chain forming (ATP.DnaK)m.substrate.DnaJn complexes; in these ternary complexes efficient cis-interaction of the J-domain of DnaJ with DnaK is favored by their propinquity and triggers the hydrolysis of DnaK-bound ATP, converting DnaK to its ADP-liganded high affinity state and thus locking it onto the substrate polypeptide.
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Affiliation(s)
- Wanjiang Han
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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47
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Flanagan JM, Bewley MC. Protein quality control in bacterial cells: integrated networks of chaperones and ATP-dependent proteases. GENETIC ENGINEERING 2003; 24:17-47. [PMID: 12416299 DOI: 10.1007/978-1-4615-0721-5_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- John M Flanagan
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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48
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Toutain CM, Clarke DJ, Leeds JA, Kuhn J, Beckwith J, Holland IB, Jacq A. The transmembrane domain of the DnaJ-like protein DjlA is a dimerisation domain. Mol Genet Genomics 2003; 268:761-70. [PMID: 12655402 DOI: 10.1007/s00438-002-0793-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2002] [Accepted: 12/03/2002] [Indexed: 11/24/2022]
Abstract
DjlA is a bitopic inner membrane protein, which belongs to the DnaJ co-chaperone family in Escherichia coli. Overproduction of DjlA leads to the synthesis of colanic acid, resulting in mucoidy, via the activation of the two-component regulatory system RcsC/B that controls the cps (capsular polysaccharide) operon. This induction requires both the co-chaperone activity of DjlA, in cooperation with DnaK and GrpE, and its unique transmembrane (TM) domain. Here, we show that the TM segment of DjlA acts as a dimerisation domain: when fused to the N-terminal DNA-binding domain of the lambda cI repressor protein, it can substitute for the native C-terminal dimerisation domain of cI, thus generating an active cI repressor. Replacing the TM domain of DjlA by other TM domains, with or without dimerising capacity, revealed that dimerisation is not sufficient for the induction of cps expression, indicating an additional sequence- or structurally specific role for the TM domain. Finally, the conserved glycines present in the TM domain of DjlA are essential for the induction of mucoidy, but not for dimerisation.
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Affiliation(s)
- C M Toutain
- Institut de Génétique et Microbiologie, UMR CNRS 8621, Bâtiment 400, Université Paris-Sud, 91405 Orsay, France
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Majdalani N, Hernandez D, Gottesman S. Regulation and mode of action of the second small RNA activator of RpoS translation, RprA. Mol Microbiol 2002; 46:813-26. [PMID: 12410838 DOI: 10.1046/j.1365-2958.2002.03203.x] [Citation(s) in RCA: 269] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Translation of the stationary phase sigma factor RpoS is stimulated by at least two small RNAs, DsrA and RprA. DsrA disrupts an inhibitory secondary structure in the rpoS leader mRNA by pairing with the upstream RNA. Mutations in rprA and compensating mutations in the rpoS leader demonstrate that RprA interacts with the same region of the RpoS leader as DsrA. This is the first example of two different small RNAs regulating a common target. Regulation of these RNAs differs. DsrA synthesis is increased at low temperature. We find that RprA synthesis is regulated by the RcsC/RcsB phosphorelay system, previously found to regulate capsule synthesis and promoters of ftsZ and osmC. An rcsB null mutation abolishes the basal level, whereas mutations in rcsC that activate capsule synthesis also activate expression of the rprA promoter. An essential site with similarity to other RcsB-regulated promoters was defined in the rprA promoter. Activation of the RcsC/RcsB system leads to increased RpoS synthesis, in an RprA-dependent fashion. This work suggests a new signal for RpoS translation and extends the global regulation effected by the RcsC/RcsB system to coregulation of RpoS with capsule and FtsZ.
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Affiliation(s)
- Nadim Majdalani
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4264, USA
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Genevaux P, Schwager F, Georgopoulos C, Kelley WL. Scanning mutagenesis identifies amino acid residues essential for the in vivo activity of the Escherichia coli DnaJ (Hsp40) J-domain. Genetics 2002; 162:1045-53. [PMID: 12454054 PMCID: PMC1462316 DOI: 10.1093/genetics/162.3.1045] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The DnaJ (Hsp40) cochaperone regulates the DnaK (Hsp70) chaperone by accelerating ATP hydrolysis in a cycle closely linked to substrate binding and release. The J-domain, the signature motif of the Hsp40 family, orchestrates interaction with the DnaK ATPase domain. We studied the J-domain by creating 42 mutant E. coli DnaJ variants and examining their phenotypes in various separate in vivo assays, namely, bacterial growth at low and high temperatures, motility, and propagation of bacteriophage lambda. Most mutants studied behaved like wild type in all assays. In addition to the (33)HisProAsp(35) (HPD) tripeptide found in all known functional J-domains, our study uncovered three new single substitution mutations (Y25A, K26A, and F47A) that totally abolish J-domain function. Furthermore, two glycine substitution mutants in an exposed flexible loop (R36G, N37G) showed partial loss of J-domain function alone and complete loss of function as a triple (RNQ-GGG) mutant coupled with the phenotypically silent Q38G. Interestingly, all the essential residues map to a small region on the same solvent-exposed face of the J-domain. Engineered mutations in the corresponding residues of the human Hdj1 J-domain grafted in E. coli DnaJ also resulted in loss of function, suggesting an evolutionarily conserved interaction surface. We propose that these clustered residues impart critical sequence determinants necessary for J-domain catalytic activity and reversible contact interface with the DnaK ATPase domain.
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Affiliation(s)
- Pierre Genevaux
- Département de Biochimie Médicale, Centre Médical Universitaire, CH-1211 Geneva 4, Switzerland.
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