1
|
Wessel AK, Yoshii Y, Reder A, Boudjemaa R, Szczesna M, Betton JM, Bernal-Bayard J, Beloin C, Lopez D, Völker U, Ghigo JM. Escherichia coli SPFH Membrane Microdomain Proteins HflKC Contribute to Aminoglycoside and Oxidative Stress Tolerance. Microbiol Spectr 2023; 11:e0176723. [PMID: 37347165 PMCID: PMC10434171 DOI: 10.1128/spectrum.01767-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
Many eukaryotic membrane-dependent functions are often spatially and temporally regulated by membrane microdomains (FMMs), also known as lipid rafts. These domains are enriched in polyisoprenoid lipids and scaffolding proteins belonging to the stomatin, prohibitin, flotillin, and HflK/C (SPFH) protein superfamily that was also identified in Gram-positive bacteria. In contrast, little is still known about FMMs in Gram-negative bacteria. In Escherichia coli K-12, 4 SPFH proteins, YqiK, QmcA, HflK, and HflC, were shown to localize in discrete polar or lateral inner membrane locations, raising the possibility that E. coli SPFH proteins could contribute to the assembly of inner membrane FMMs and the regulation of cellular processes. Here, we studied the determinant of the localization of QmcA and HflC and showed that FMM-associated cardiolipin lipid biosynthesis is required for their native localization pattern. Using Biolog phenotypic arrays, we showed that a mutant lacking all SPFH genes displayed increased sensitivity to aminoglycosides and oxidative stress that is due to the absence of HflKC. Our study therefore provides further insights into the contribution of SPFH proteins to stress tolerance in E. coli. IMPORTANCE Eukaryotic cells often segregate physiological processes in cholesterol-rich functional membrane microdomains. These domains are also called lipid rafts and contain proteins of the stomatin, prohibitin, flotillin, and HflK/C (SPFH) superfamily, which are also present in prokaryotes but have been mostly studied in Gram-positive bacteria. Here, we showed that the cell localization of the SPFH proteins QmcA and HflKC in the Gram-negative bacterium E. coli is altered in the absence of cardiolipin lipid synthesis. This suggests that cardiolipins contribute to E. coli membrane microdomain assembly. Using a broad phenotypic analysis, we also showed that HflKC contribute to E. coli tolerance to aminoglycosides and oxidative stress. Our study, therefore, provides new insights into the cellular processes associated with SPFH proteins in E. coli.
Collapse
Affiliation(s)
- Aimee K. Wessel
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
| | - Yutaka Yoshii
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
| | - Alexander Reder
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | | | - Magdalena Szczesna
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
- Centre for Bacteriology Resistance Biology, Imperial College London, London, United Kingdom
| | - Jean-Michel Betton
- Institut Pasteur, Université de Paris-Cité, UMR UMR6047, Stress adaptation and metabolism in enterobacteria, Paris, France
| | - Joaquin Bernal-Bayard
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Christophe Beloin
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
| | - Daniel Lopez
- Universidad Autonoma de Madrid, Centro Nacional de Biotecnologia, Madrid, Spain
| | - Uwe Völker
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Jean-Marc Ghigo
- Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France
| |
Collapse
|
2
|
Tsviklist V, Guest RL, Raivio TL. The Cpx Stress Response Regulates Turnover of Respiratory Chain Proteins at the Inner Membrane of Escherichia coli. Front Microbiol 2022; 12:732288. [PMID: 35154019 PMCID: PMC8831704 DOI: 10.3389/fmicb.2021.732288] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 12/20/2021] [Indexed: 12/03/2022] Open
Abstract
The Cpx envelope stress response is a major signaling pathway monitoring bacterial envelope integrity, activated both internally by excessive synthesis of membrane proteins and externally by a variety of environmental cues. The Cpx regulon is enriched with genes coding for protein folding and degrading factors, virulence determinants, and large envelope-localized complexes. Transcriptional repression of the two electron transport chain complexes, NADH dehydrogenase I and cytochrome bo3, by the Cpx pathway has been demonstrated, however, there is evidence that additional regulatory mechanisms exist. In this study, we examine the interaction between Cpx-regulated protein folding and degrading factors and the respiratory complexes NADH dehydrogenase I and succinate dehydrogenase in Escherichia coli. Here we show that the cellular need for Cpx-mediated stress adaptation increases when respiratory complexes are more prevalent or active, which is demonstrated by the growth defect of Cpx-deficient strains on media that requires a functional electron transport chain. Interestingly, deletion of several Cpx-regulated proteolytic factors and chaperones results in similar growth-deficient phenotypes. Furthermore, we find that the stability of the NADH dehydrogenase I protein complex is lower in cells with a functional Cpx response, while in its absence, protein turnover is impaired. Finally, we demonstrated that the succinate dehydrogenase complex has reduced activity in E. coli lacking the Cpx pathway. Our results suggest that the Cpx two-component system serves as a sentry of inner membrane protein biogenesis, ensuring the function of large envelope protein complexes and maintaining the cellular energy status of the cell.
Collapse
Affiliation(s)
- Valeria Tsviklist
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Randi L. Guest
- Lewis Thomas Laboratory, Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Tracy L. Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- *Correspondence: Tracy L. Raivio,
| |
Collapse
|
3
|
Bothammal P, Ganesh M, Vigneshwaran V, Anbarasu K, Ponmurugan K, Al-Dhabi NA, Natarajaseenivasan K. Construction of Genomic Library and Screening of Edwardsiella tarda Immunogenic Proteins for Their Protective Efficacy Against Edwardsiellosis. Front Immunol 2021; 12:764662. [PMID: 34868012 PMCID: PMC8636194 DOI: 10.3389/fimmu.2021.764662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022] Open
Abstract
Edwardsiella tarda is a severe aquaculture pathogen that can infect many hosts including humans, animals, and fish. Timely diagnosis and treatment are crucial for the control of edwardsiellosis in the aqua industry. By using rabbit polyclonal antibody, an expression gene library of virulent Edwardsiella tarda strain ED-BDU 1 isolated in south India was constructed and screened. The identified immune expressive proteins were characterized, and the corresponding coding sequences were cloned, expressed, and the purified recombinant proteins were used as antigens. The identified immunoreactive proteins namely HflC, HflK, and YhcI were studied for their immune protective potential in vivo by challenge experiments. The protective efficacy of HflC, HflK, and YhcI showed that the clearance of Edwardsiella from the host with ~ 60% survivability. Further, the immunoreactive proteins induce a strong immune response upon infection and elicit the significant production of IL-10, IFN-γ, Th1, and Th2 mediated mRNA expression and were therefore effective in vaccine production for edwardsiellosis.
Collapse
Affiliation(s)
- Palanisamy Bothammal
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Mohan Ganesh
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Vellaisamy Vigneshwaran
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Kumarasamy Anbarasu
- Microbial Biotechnology Laboratory, Department of Marine Biotechnology, School of Marine Sciences, Bharathidasan University, Tiruchirappalli, India
| | - Karuppiah Ponmurugan
- Department of Botany & Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Naif Abdullah Al-Dhabi
- Department of Botany & Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Kalimuthusamy Natarajaseenivasan
- Medical Microbiology Laboratory, Department of Microbiology, Center for Excellence in Life Sciences, Bharathidasan University, Tiruchirappalli, India
| |
Collapse
|
4
|
Srinivasan K, Banerjee A, Baid P, Dhur A, Sengupta J. Ribosome-membrane crosstalk: Co-translational targeting pathways of proteins across membranes in prokaryotes and eukaryotes. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:163-198. [PMID: 35034718 DOI: 10.1016/bs.apcsb.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ribosomes are the molecular machine of living cells designed for decoding mRNA-encoded genetic information into protein. Being sophisticated machinery, both in design and function, the ribosome not only carries out protein synthesis, but also coordinates several other ribosome-associated cellular processes. One such process is the translocation of proteins across or into the membrane depending on their secretory or membrane-associated nature. These proteins comprise a large portion of a cell's proteome and act as key factors for cellular survival as well as several crucial functional pathways. Protein transport to extra- and intra-cytosolic compartments (across the eukaryotic endoplasmic reticulum (ER) or across the prokaryotic plasma membrane) or insertion into membranes majorly occurs through an evolutionarily conserved protein-conducting channel called translocon (eukaryotic Sec61 or prokaryotic SecYEG channels). Targeting proteins to the membrane-bound translocon may occur via post-translational or co-translational modes and it is often mediated by recognition of an N-terminal signal sequence in the newly synthesizes polypeptide chain. Co-translational translocation is coupled to protein synthesis where the ribosome-nascent chain complex (RNC) itself is targeted to the translocon. Here, in the light of recent advances in structural and functional studies, we discuss our current understanding of the mechanistic models of co-translational translocation, coordinated by the actively translating ribosomes, in prokaryotes and eukaryotes.
Collapse
Affiliation(s)
- Krishnamoorthi Srinivasan
- Division of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Aneek Banerjee
- Division of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Priya Baid
- Division of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Ankit Dhur
- Division of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Jayati Sengupta
- Division of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
| |
Collapse
|
5
|
Furukawa A, Nakayama S, Yoshikaie K, Tanaka Y, Tsukazaki T. Remote Coupled Drastic β-Barrel to β-Sheet Transition of the Protein Translocation Motor. Structure 2018; 26:485-489.e2. [PMID: 29398525 DOI: 10.1016/j.str.2018.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/27/2017] [Accepted: 01/05/2018] [Indexed: 10/18/2022]
Abstract
The membrane protein SecDF, belonging to the RND superfamily, enhances protein translocation at the extracytoplasmic side using a proton gradient. Here, we report the crystal structure of SecDF in a form we named Super-membrane-facing (Super F) form, demonstrating a β-barrel architecture instead of the previously reported β-sheet structure. Through this structural insight and supporting results of an in vivo crosslinking experiment, we propose a remote coupling model in which a structural change of the transmembrane region drives a functional, extracytoplasmic conformational transition.
Collapse
Affiliation(s)
- Arata Furukawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Shintaro Nakayama
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Kunihito Yoshikaie
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Yoshiki Tanaka
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Tomoya Tsukazaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
| |
Collapse
|
6
|
Wang S, Yang CI, Shan SO. SecA mediates cotranslational targeting and translocation of an inner membrane protein. J Cell Biol 2017; 216:3639-3653. [PMID: 28928132 PMCID: PMC5674894 DOI: 10.1083/jcb.201704036] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 07/17/2017] [Accepted: 08/02/2017] [Indexed: 12/02/2022] Open
Abstract
Proteins are thought to be delivered to the bacterial plasma membrane cotranslationally by signal recognition particle or posttranslationally by SecA. Wang et al. identify a new membrane protein–targeting pathway in bacteria in which SecA cotranslationally recognizes and targets the inner membrane protein RodZ, which harbors an internal transmembrane domain. Protein targeting to the bacterial plasma membrane was generally thought to occur via two major pathways: cotranslational targeting by signal recognition particle (SRP) and posttranslational targeting by SecA and SecB. Recently, SecA was found to also bind ribosomes near the nascent polypeptide exit tunnel, but the function of this SecA–ribosome contact remains unclear. In this study, we show that SecA cotranslationally recognizes the nascent chain of an inner membrane protein, RodZ, with high affinity and specificity. In vitro reconstitution and in vivo targeting assays show that SecA is necessary and sufficient to direct the targeting and translocation of RodZ to the bacterial plasma membrane in an obligatorily cotranslational mechanism. Sequence elements upstream and downstream of the RodZ transmembrane domain dictate nascent polypeptide selection by SecA instead of the SRP machinery. These findings identify a new route for the targeting of inner membrane proteins in bacteria and highlight the diversity of targeting pathways that enables an organism to accommodate diverse nascent proteins.
Collapse
Affiliation(s)
- Shuai Wang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Chien-I Yang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| |
Collapse
|
7
|
Bay DC, Chan CS, Turner RJ. NarJ subfamily system specific chaperone diversity and evolution is directed by respiratory enzyme associations. BMC Evol Biol 2015; 15:110. [PMID: 26067063 PMCID: PMC4464133 DOI: 10.1186/s12862-015-0412-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 06/04/2015] [Indexed: 12/04/2022] Open
Abstract
Background Redox enzyme maturation proteins (REMPs) describe a diverse family of prokaryotic chaperones involved in the biogenesis of anaerobic complex iron sulfur molybdoenzyme (CISM) respiratory systems. Many REMP family studies have focused on NarJ subfamily members from Escherichia coli: NarJ, NarW, DmsD, TorD and YcdY. The aim of this bioinformatics study was to expand upon the evolution, distribution and genetic association of these 5 REMP members within 130 genome sequenced taxonomically diverse species representing 324 Prokaryotic sequences. NarJ subfamily member diversity was examined at the phylum-species level and at the amino acid/nucleotide level to determine how close their genetic associations were between their respective CISM systems within phyla. Results This study revealed that NarJ members possessed unique motifs that distinguished Gram-negative from Gram-positive/Archaeal species and identified a strict genetic association with its nitrate reductase complex (narGHI) operon compared to all other members. NarW appears to be found specifically in Gammaproteobacteria. DmsD also showed close associations with the dimethylsulfoxide reductase (dmsABC) operon compared to TorD. Phylogenetic analysis revealed that YcdY has recently evolved from DmsD and that YcdY has likely diverged into 2 subfamilies linked to Zn- dependent alkaline phosphatase (ycdX) operons and a newly identified operon containing part of Zn-metallopeptidase FtsH complex component (hflC) and NADH-quinone dehydrogenase (mdaB). TorD demonstrated the greatest diversity in operon association. TorD was identifed within operons from either trimethylamine-N-oxide reductase (torAC) or formate dehydrogenase (fdhGHI), where each type of TorD had a unique motif. Additionally a subgroup of dmsD and torD members were also linked to operons with biotin sulfoxide (bisC) and polysulfide reductase (nrfD) indicating a potential role in the maturation of diverse CISM. Conclusion Examination of diverse prokaryotic NarJ subfamily members demonstrates that the evolution and genetic association of each member is uniquely biased by its CISM operon association. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0412-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Denice C Bay
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
| | - Catherine S Chan
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, Rm 156 Biological Science Bldg., 2500 University Dr. NW, Calgary, T2N 1 N4, AB, Canada.
| |
Collapse
|
8
|
ZnO nanoparticles impose a panmetabolic toxic effect along with strong necrosis, inducing activation of the envelope stress response in Salmonella enterica serovar Enteritidis. Antimicrob Agents Chemother 2015; 59:3317-28. [PMID: 25801570 DOI: 10.1128/aac.00363-15] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/17/2015] [Indexed: 11/20/2022] Open
Abstract
In this study, we tested the antimicrobial activity of three metal nanoparticles (NPs), ZnO, MgO, and CaO NPs, against Salmonella enterica serovar Enteritidis in liquid medium and on solid surfaces. Out of the three tested metal NPs, ZnO NPs exhibited the most significant antimicrobial effect both in liquid medium and when embedded on solid surfaces. Therefore, we focused on revealing the mechanisms of surface-associated ZnO biocidal activity. Using the global proteome approach, we report that a great majority (79%) of the altered proteins in biofilms formed by Salmonella enterica serovar Enteritidis were downregulated, whereas a much smaller fraction (21%) of proteins were upregulated. Intriguingly, all downregulated proteins were enzymes involved in a wide range of the central metabolic pathways, including translation; amino acid biosynthetic pathways; nucleobase, nucleoside, and nucleotide biosynthetic processes; ATP synthesis-coupled proton transport; the pentose phosphate shunt; and carboxylic acid metabolic processes, indicating that ZnO NPs exert a panmetabolic toxic effect on this prokaryotic organism. In addition to their panmetabolic toxicity, ZnO NPs induced profound changes in cell envelope morphology, imposing additional necrotic effects and triggering the envelope stress response of Salmonella serovar Enteritidis. The envelope stress response effect activated periplasmic chaperones and proteases, transenvelope complexes, and regulators, thereby facilitating protection of this prokaryotic organism against ZnO NPs.
Collapse
|
9
|
MacRitchie DM, Acosta N, Raivio TL. DegP is involved in Cpx-mediated posttranscriptional regulation of the type III secretion apparatus in enteropathogenic Escherichia coli. Infect Immun 2012; 80:1766-72. [PMID: 22331433 PMCID: PMC3347454 DOI: 10.1128/iai.05679-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 01/29/2012] [Indexed: 11/20/2022] Open
Abstract
The Cpx envelope stress response facilitates adaptation to envelope stresses that lead to the misfolding of periplasmic proteins. Cpx-mediated adaptation involves elevated expression of periplasmic proteases and chaperones. Previously, we demonstrated that induction of the Cpx envelope stress response in enteropathogenic Escherichia coli (EPEC) also results in inhibition of type III secretion (T3S) and that this is correlated with downregulated transcription of the relevant genes. Here, we investigated whether the Cpx stress response might also exert posttranscriptional effects on the T3S apparatus. We show that DsbA is required for T3S, while removal of transcription factor CpxR or the Cpx-regulated folding factor CpxP or PpiA has minimal effects. Conversely, the entire T3S complex is removed from the envelope when the Cpx response is activated. Overexpression of the chaperone/protease DegP mimics the Cpx-dependent inhibition of the T3S complex at a posttranscriptional level, and mutation of degP partly abrogates the ability of the Cpx response to inhibit the T3S complex and motility. We present data that suggest that both the protease and chaperone activities of DegP are likely important for the impact on T3S. Altogether, our data indicate that DegP is normally a part of the Cpx-mediated inhibition of virulence determinant expression in EPEC and that additional factors are involved.
Collapse
Affiliation(s)
- Dawn M MacRitchie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | | | | |
Collapse
|
10
|
Weski J, Meltzer M, Spaan L, Mönig T, Oeljeklaus J, Hauske P, Vouilleme L, Volkmer R, Boisguerin P, Boyd D, Huber R, Kaiser M, Ehrmann M. Chemical Biology Approaches Reveal Conserved Features of a C-Terminal Processing PDZ Protease. Chembiochem 2012; 13:402-8. [DOI: 10.1002/cbic.201100643] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Indexed: 12/21/2022]
|
11
|
Bandyopadhyay K, Parua PK, Datta AB, Parrack P. Escherichia coli HflK and HflC can individually inhibit the HflB (FtsH)-mediated proteolysis of lambdaCII in vitro. Arch Biochem Biophys 2010; 501:239-43. [PMID: 20599668 DOI: 10.1016/j.abb.2010.06.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 06/14/2010] [Accepted: 06/25/2010] [Indexed: 11/25/2022]
Abstract
LambdaCII is the key protein that influences the lysis/lysogeny decision of lambda by activating several phage promoters. The effect of CII is modulated by a number of phage and host proteins including Escherichia coli HflK and HflC. These membrane proteins copurify as a tightly bound complex 'HflKC' that inhibits the HflB (FtsH)-mediated proteolysis of CII both in vitro and in vivo. Individual purification of HflK and HflC has not been possible so far, since each requires the presence of the other for proper folding. We report the first purification of HflK and HflC separately as active and functional proteins and show that each can interact with HflB on its own and each inhibits the proteolysis of CII. They also inhibit the proteolysis of E. coli sigma(32) by HflB. We show that at low concentrations each protein is dimeric, based on which we propose a scheme for the mutual interactions of HflB, HflK and HflC in a supramolecular HflBKC protease complex.
Collapse
Affiliation(s)
- Kaustav Bandyopadhyay
- Department of Biochemistry, Bose Institute P-1/12, C.I.T. Scheme VIIM, Kolkata 700 054, India
| | | | | | | |
Collapse
|
12
|
Yusa F, Steiner JM, Löffelhardt W. Evolutionary conservation of dual Sec translocases in the cyanelles of Cyanophora paradoxa. BMC Evol Biol 2008; 8:304. [PMID: 18976493 PMCID: PMC2600650 DOI: 10.1186/1471-2148-8-304] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Accepted: 11/01/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cyanelles, the peptidoglycan-armored plastids of glaucocystophytes, occupy a unique bridge position in between free-living cyanobacteria and chloroplasts. In some respects they side with cyanobacteria whereas other features are clearly shared with chloroplasts. The Sec translocase, an example for "conservative sorting" in the course of evolution, is found in the plasma membrane of all prokaryotes, in the thylakoid membrane of chloroplasts and in both these membrane types of cyanobacteria. RESULTS In this paper we present evidence for a dual location of the Sec translocon in the thylakoid as well as inner envelope membranes of the cyanelles from Cyanophora paradoxa, i. e. conservative sorting sensu stricto. The prerequisite was the generation of specific antisera directed against cyanelle SecY that allowed immunodetection of the protein on SDS gels from both membrane types separated by sucrose density gradient floatation centrifugation. Immunoblotting of blue-native gels yielded positive but differential results for both the thylakoid and envelope Sec complexes, respectively. In addition, heterologous antisera directed against components of the Toc/Tic translocons and binding of a labeled precursor protein were used to discriminate between inner and outer envelope membranes. CONCLUSION The envelope translocase can be envisaged as a prokaryotic feature missing in higher plant chloroplasts but retained in cyanelles, likely for protein transport to the periplasm. Candidate passengers are cytochrome c6 and enzymes of peptidoglycan metabolism. The minimal set of subunits of the Toc/Tic translocase of a primitive plastid is proposed.
Collapse
Affiliation(s)
- Fumie Yusa
- SLT, Nagahama-city, Shiga-ken 526-0829, Japan.
| | | | | |
Collapse
|
13
|
Zweers JC, Barák I, Becher D, Driessen AJ, Hecker M, Kontinen VP, Saller MJ, Vavrová L, van Dijl JM. Towards the development of Bacillus subtilis as a cell factory for membrane proteins and protein complexes. Microb Cell Fact 2008; 7:10. [PMID: 18394159 PMCID: PMC2323362 DOI: 10.1186/1475-2859-7-10] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2007] [Accepted: 04/04/2008] [Indexed: 01/16/2023] Open
Abstract
Background The Gram-positive bacterium Bacillus subtilis is an important producer of high quality industrial enzymes and a few eukaryotic proteins. Most of these proteins are secreted into the growth medium, but successful examples of cytoplasmic protein production are also known. Therefore, one may anticipate that the high protein production potential of B. subtilis can be exploited for protein complexes and membrane proteins to facilitate their functional and structural analysis. The high quality of proteins produced with B. subtilis results from the action of cellular quality control systems that efficiently remove misfolded or incompletely synthesized proteins. Paradoxically, cellular quality control systems also represent bottlenecks for the production of various heterologous proteins at significant concentrations. Conclusion While inactivation of quality control systems has the potential to improve protein production yields, this could be achieved at the expense of product quality. Mechanisms underlying degradation of secretory proteins are nowadays well understood and often controllable. It will therefore be a major challenge for future research to identify and modulate quality control systems of B. subtilis that limit the production of high quality protein complexes and membrane proteins, and to enhance those systems that facilitate assembly of these proteins.
Collapse
Affiliation(s)
- Jessica C Zweers
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, P,O, Box 30001, 9700 RB Groningen, The Netherlands.
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Shimohata N, Nagamori S, Akiyama Y, Kaback HR, Ito K. SecY alterations that impair membrane protein folding and generate a membrane stress. ACTA ACUST UNITED AC 2007; 176:307-17. [PMID: 17242069 PMCID: PMC2063957 DOI: 10.1083/jcb.200611121] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report on a class of Escherichia coli SecY mutants that impair membrane protein folding. The mutants also up-regulate the Cpx/σE stress response pathways. Similar stress induction was also observed in response to a YidC defect in membrane protein biogenesis but not in response to the signal recognition particle–targeting defect or in response to a simple reduction in the abundance of the translocon. Together with the previous contention that the Cpx system senses a protein abnormality not only at periplasmic and outer membrane locations but also at the plasma membrane, abnormal states of membrane proteins are postulated to be generated in these secY mutants. In support of this notion, in vitro translation, membrane integration, and folding of LacY reveal that mutant membrane vesicles allow the insertion of LacY but not subsequent folding into a normal conformation recognizable by conformation-specific antibodies. The results demonstrate that normal SecY function is required for the folding of membrane proteins after their insertion into the translocon.
Collapse
Affiliation(s)
- Nobuyuki Shimohata
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | | | | | | | | |
Collapse
|
15
|
Browman DT, Resek ME, Zajchowski LD, Robbins SM. Erlin-1 and erlin-2 are novel members of the prohibitin family of proteins that define lipid-raft-like domains of the ER. J Cell Sci 2006; 119:3149-60. [PMID: 16835267 DOI: 10.1242/jcs.03060] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Our laboratory was interested in characterizing the molecular composition of non-caveolar lipid rafts. Thus, we generated monoclonal antibodies to lipid raft proteins of human myelomonocytic cells. Two of these proteins, KE04p and C8orf2, were found to be highly enriched in the detergent-insoluble, buoyant fraction of sucrose gradients in a cholesterol-dependent manner. They contain an evolutionarily conserved domain placing them in the prohibitin family of proteins. In contrast to other family members, these two proteins localized to the ER. Furthermore, the extreme N-termini of KE04p and C8orf2 were found to be sufficient for heterologous targeting of GFP to the ER in the absence of classical ER retrieval motifs. We also demonstrate that all prohibitin family members rely on sequences in their extreme N-termini for their distinctive subcellular distributions including the mitochondria, plasma membrane and Golgi vesicles. Owing to their subcellular localization and their presence in lipid rafts, we have named KE04p and C8orf2, ER lipid raft protein (erlin)-1 and erlin-2, respectively. Interestingly, the ER contains relatively low levels of cholesterol and sphingolipids compared with other organelles. Thus, our data support the existence of lipid-raft-like domains within the membranes of the ER.
Collapse
Affiliation(s)
- Duncan T Browman
- Southern Alberta Cancer Research Institute, Departments of Oncology and Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | | | | | | |
Collapse
|
16
|
Chiba S, Ito K, Akiyama Y. The Escherichia coli plasma membrane contains two PHB (prohibitin homology) domain protein complexes of opposite orientations. Mol Microbiol 2006; 60:448-57. [PMID: 16573693 DOI: 10.1111/j.1365-2958.2006.05104.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two membrane proteases, FtsH and HtpX, are jointly essential for Escherichia coli cell viability, presumably through their abilities to degrade abnormal membrane proteins. To search for additional cellular factors involved in membrane protein quality control, we isolated multicopy suppressors that alleviated the growth defect of the ftsH/htpX dual disruption mutant. One of them was ybbK, which is renamed qmcA, encoding a membrane-bound prohibitin homology (PHB) domain family protein. Multicopy suppression was also observed with hflK-hflC, encoding another set of PHB domain membrane proteins, which had been known to form a complex (HflKC) and to interact with FtsH. Whereas the DeltaftsH sfhC21 (a viability defect suppressor for DeltaftsH) strain exhibited temperature sensitivity in the presence of cAMP, additional disruption of both qmcA and hflK-hflC exaggerated the growth defect. Pull-down and sedimentation experiments showed that QmcA, like HflKC, forms an oligomer and interacts with FtsH. Protease accessibility assays revealed that QmcA, unlike periplasmically exposed HflKC, possesses a cytoplasmically disposed large C-terminal domain, thus assuming the type I (NOUT-CIN) orientation. We discuss possible significance of having PHB domains on both sides of the membrane.
Collapse
Affiliation(s)
- Shinobu Chiba
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | | | | |
Collapse
|
17
|
Briere LAK, Dunn SD. The Periplasmic Domains of Escherichia coli HflKC Oligomerize through Right-Handed Coiled-Coil Interactions. Biochemistry 2006; 45:8607-16. [PMID: 16834335 DOI: 10.1021/bi0606997] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The periplasmic domains of the Escherichia coli HflK and HflC were coexpressed and purified. The two polypeptides copurified in a 1:1 ratio, as determined by quantitative amino acid analysis. Circular dichroism studies showed the complex to have substantial helical/coiled-coil content that melted with midpoints in the range of 26-29 degrees C depending upon the concentration, implying a reversible oligomerization. The average molecular weight of the soluble HflKC determined by sedimentation equilibrium ultracentrifugation using a single-species model varied with rotor speed, providing further evidence of concentration-dependent oligomerization. The data were well-fit by models that specified a protomer to n-mer oligomerization, with the heterodimeric HflKC as the protomer and values of n between 7 and 10. Multiple-sequence alignments of both HflK and HflC revealed regions near the C termini to contain 11-residue hendecad repeats, indicative of right-handed coiled coils, with characteristic small residues in the a, f, h, and j positions. To test the importance of the small size of these positions, two residues in the HflC domain, Ala-262 in a f position and Gly-268 in an a position, were mutated to isoleucine. The HflKC:A262I mutant complex showed lower helicity than the wild type, and its melting was less concentration-dependent. During purification of HflKC:G268I, the mutated HflC subunit precipitated, leaving a preparation of the pure peripheral HflK domain. This polypeptide behaved as a monomer in sedimentation equilibrium experiments and showed low helicity, implying that the protein conformation is largely dependent upon heteromeric subunit interactions. These results demonstrate the importance of right-handed coiled-coil interactions in the oligomerization of HflKC, and a model entailing the formation of a right-handed helical barrel is proposed.
Collapse
Affiliation(s)
- Lee-Ann K Briere
- Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | | |
Collapse
|
18
|
Abstract
FtsH is a cytoplasmic membrane protein that has N-terminally located transmembrane segments and a main cytosolic region consisting of AAA-ATPase and Zn2+-metalloprotease domains. It forms a homo-hexamer, which is further complexed with an oligomer of the membrane-bound modulating factor HflKC. FtsH degrades a set of short-lived proteins, enabling cellular regulation at the level of protein stability. FtsH also degrades some misassembled membrane proteins, contributing to their quality maintenance. It is an energy-utilizing and processive endopeptidase with a special ability to dislocate membrane protein substrates out of the membrane, for which its own membrane-embedded nature is essential. We discuss structure-function relationships of this intriguing enzyme, including the way it recognizes the soluble and membrane-integrated substrates differentially, on the basis of the solved structure of the ATPase domain as well as extensive biochemical and genetic information accumulated in the past decade on this enzyme.
Collapse
Affiliation(s)
- Koreaki Ito
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
| | | |
Collapse
|
19
|
Shimohata N, Akiyama Y, Ito K. Peculiar properties of DsbA in its export across the Escherichia coli cytoplasmic membrane. J Bacteriol 2005; 187:3997-4004. [PMID: 15937162 PMCID: PMC1151732 DOI: 10.1128/jb.187.12.3997-4004.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Export of DsbA, a protein disulfide bond-introducing enzyme, across the Escherichia coli cytoplasmic membrane was studied with special reference to the effects of various mutations affecting translocation factors. It was noted that both the internalized precursor retaining the signal peptide and the periplasmic mature product fold rapidly into a protease-resistant structure and they exhibited anomalies in sodium dodecyl sulfate-polyacrylamide gel electrophoresis in that the former migrated faster than the latter. The precursor, once accumulated, was not exported posttranslationally. DsbA export depended on the SecY translocon, the SecA ATPase, and Ffh (signal recognition particle), but not on SecB. SecY mutations, such as secY39 and secY205, that severely impair translocation of a number of secretory substrates by interfering with SecA actions only insignificantly impaired the DsbA export. In contrast, secY125, affecting a periplasmic domain and impairing a late step of translocation, exerted strong export inhibition of both classes of proteins. These results suggest that DsbA uses not only the signal recognition particle targeting pathway but also a special route of translocation through the translocon, which is hence suggested to actively discriminate pre-proteins.
Collapse
|
20
|
Saikawa N, Akiyama Y, Ito K. FtsH exists as an exceptionally large complex containing HflKC in the plasma membrane of Escherichia coli. J Struct Biol 2004; 146:123-9. [PMID: 15037243 DOI: 10.1016/j.jsb.2003.09.020] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Indexed: 10/26/2022]
Abstract
FtsH is an ATP-dependent and membrane-associated protease, which exerts processive proteolysis against membrane-embedded and soluble substrate proteins. Although previous studies suggested that it functions as a homo-oligomer and it also interacts with HflK-HflC membrane protein complex (HflKC), it is still important to address the question of what kind of supramolecular assembly FtsH forms in wild-type cells. Now we show that FtsH in wild-type Escherichia coli cells exists exclusively as a large complex, termed FtsH holo-enzyme, which can be separated from bulk of membrane proteins after detergent solubilization and velocity sedimentation. This complex appears to have molecular mass of around 1000 kDa. A tentative model is presented that it is composed of hexamers of FtsH and of HflKC, with an ability to bind one or a few substrate molecules.
Collapse
Affiliation(s)
- Naoya Saikawa
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | | | | |
Collapse
|
21
|
Clausen T, Southan C, Ehrmann M. The HtrA family of proteases: implications for protein composition and cell fate. Mol Cell 2002; 10:443-55. [PMID: 12408815 DOI: 10.1016/s1097-2765(02)00658-5] [Citation(s) in RCA: 477] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cells precisely monitor the concentration and functionality of each protein for optimal performance. Protein quality control involves molecular chaperones, folding catalysts, and proteases that are often heat shock proteins. One quality control factor is HtrA, one of a new class of oligomeric serine proteases. The defining feature of the HtrA family is the combination of a catalytic domain with at least one C-terminal PDZ domain. Here, we discuss the properties and roles of this ATP-independent protease chaperone system in protein metabolism and cell fate.
Collapse
Affiliation(s)
- Tim Clausen
- Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Am Klopferspitz 18A, 82152 Martinsried, Germany
| | | | | |
Collapse
|
22
|
Abstract
The Sec machinery (or translocase) provides a major pathway of protein translocation from the cytosol across the cytoplasmic membrane in bacteria. The SecA ATPase interacts dynamically with the SecYEG integral membrane components to drive the transmembrane movement of newly synthesized preproteins. This pathway is also used for integration of some membrane proteins and the Sec translocase interacts with other cellular components to achieve its cellular roles. The detailed protein interactions involved in these processes are being actively studied and a structural understanding of the protein-conducting channel has started to emerge.
Collapse
Affiliation(s)
- H Mori
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | | |
Collapse
|
23
|
Kihara A, Akiyama Y, Ito K. Revisiting the lysogenization control of bacteriophage lambda. Identification and characterization of a new host component, HflD. J Biol Chem 2001; 276:13695-700. [PMID: 11278968 DOI: 10.1074/jbc.m011699200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Upon infection to the Escherichia coli cell, the genome of bacteriophage lambda either replicates to form new progenies (lytic growth) or integrates into the host chromosome (lysogenization). The lambda CII protein is a key determinant in the lysis-lysogeny decision. It is a short-lived transcription activator for the lambda genes essential for lysogeny establishment. In this study, we isolated a new class of hfl (high frequency lysogenization) mutants of E. coli, using a new selection for enhancement of CII-stimulated transcription. The gene affected was termed hflD, which encodes a protein of 213 amino acids. An hflD-disrupted mutant indeed showed an Hfl phenotype, indicating that HflD acts to down-regulate lysogenization. HflD is associated peripherally with the cytoplasmic membrane. Its interaction with CII was demonstrated in vitro using purified proteins as well as in vivo using the bacterial two-hybrid system. Pulse-chase examinations demonstrated that the HflD function is required for the rapid in vivo degradation of CII, although it interfered with FtsH-mediated CII proteolysis in an in vitro reaction system using detergent-solubilized components. We suggest that HflD is a factor that sequesters CII from the target promoters and recruits it to the membrane where the FtsH protease is localized.
Collapse
Affiliation(s)
- A Kihara
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | | | | |
Collapse
|
24
|
Müller M, Koch HG, Beck K, Schäfer U. Protein traffic in bacteria: multiple routes from the ribosome to and across the membrane. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2001; 66:107-57. [PMID: 11051763 DOI: 10.1016/s0079-6603(00)66028-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Bacteria use several routes to target their exported proteins to the plasma membrane. The majority are exported through pores formed by SecY and SecE. Two different molecular machineries are used to target proteins to the SecYE translocon. Translocated proteins, synthesized as precursors with cleavable signal sequences, require cytoplasmic chaperones, such as SecB, to remain competent for posttranslational transport. In concert with SecB, SecA targets the precursors to SecY and energizes their translocation by its ATPase activity. The latter function involves a partial insertion of SecA itself into the SecYE translocon, a process that is strongly assisted by a couple of membrane proteins, SecG, SecD, SecF, YajC, and the proton gradient across the membrane. Integral membrane proteins, however, are specifically recognized by a direct interaction between their noncleaved signal anchor sequences and the bacterial signal recognition particle (SRP) consisting of Ffh and 4.5S RNA. Recognition occurs during synthesis at the ribosome and leads to a cotranslational targeting to SecYE that is mediated by FtsY and the hydrolysis of GTP. No other Sec protein is required for integration unless the membrane protein also contains long translocated domains that engage the SecA machinery. Discrimination between SecA/SecB- and SRP-dependent targeting involves the specificity of SRP for hydrophobic signal anchor sequences and the exclusion of SRP from nascent chains of translocated proteins by trigger factor, a ribosome-associated chaperone. The SecYE pore accepts only unfolded proteins. In contrast, a class of redox factor-containing proteins leaves the cell only as completely folded proteins. They are distinguished by a twin arginine motif of their signal sequences that by an unknown mechanism targets them to specific pores. A few membrane proteins insert spontaneously into the bacterial plasma membrane without the need for targeting factors and SecYE. Insertion depends only on hydrophobic interactions between their transmembrane segments and the lipid bilayer and on the transmembrane potential. Finally, outer membrane proteins of Gram-negative bacteria after having crossed the plasma membrane are released into the periplasm, where they undergo distinct folding events until they insert as trimers into the outer membrane. These folding processes require distinct molecular chaperones of the periplasm, such as Skp, SurA, and PpiD.
Collapse
Affiliation(s)
- M Müller
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Germany
| | | | | | | |
Collapse
|
25
|
Neumann-Haefelin C, Schäfer U, Müller M, Koch HG. SRP-dependent co-translational targeting and SecA-dependent translocation analyzed as individual steps in the export of a bacterial protein. EMBO J 2000; 19:6419-26. [PMID: 11101515 PMCID: PMC305875 DOI: 10.1093/emboj/19.23.6419] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recently it has been recognized that the signal recognition particle (SRP) of Escherichia coli represents a specific targeting device for hydrophobic inner membrane proteins. It has remained unclear, however, whether the bacterial SRP functions in concert with SecA, which is required for the translocation of secretory proteins across the inner membrane. Here, we have analyzed a hybrid protein constructed by fusing the signal anchor sequence of an SRP-dependent inner membrane protein (MtlA) to the mature part of an exclusively SecA-requiring secretory protein (OmpA). We show that the signal anchor sequence of MtlA confers the novel properties onto nascent chains of OmpA of being co-translationally recognized and targeted to SecY by SRP. Once targeted to SecY, ribosome-associated nascent chains of the hybrid protein, however, remain untranslocated unless SecA is present. These results indicate that SRP and SecA cooperate in a sequential, non-overlapping manner in the topogenesis of those membrane proteins which, in addition to a signal anchor sequence, harbor a substantial hydrophilic domain to be translocated into the periplasm.
Collapse
Affiliation(s)
- C Neumann-Haefelin
- Institut für Biochemie und Molekularbiologie, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany
| | | | | | | |
Collapse
|
26
|
Nakai K. Protein sorting signals and prediction of subcellular localization. ADVANCES IN PROTEIN CHEMISTRY 2000; 54:277-344. [PMID: 10829231 DOI: 10.1016/s0065-3233(00)54009-1] [Citation(s) in RCA: 201] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- K Nakai
- Human Genome Center, Institute of Medical Science, University of Tokyo, Japan
| |
Collapse
|
27
|
Kim KI, Park SC, Kang SH, Cheong GW, Chung CH. Selective degradation of unfolded proteins by the self-compartmentalizing HtrA protease, a periplasmic heat shock protein in Escherichia coli. J Mol Biol 1999; 294:1363-74. [PMID: 10600391 DOI: 10.1006/jmbi.1999.3320] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
HtrA, which has a high molecular mass of about 500 kDa, is a periplasmic heat shock protein whose proteolytic activity is essential for the survival of Escherichia coli at high temperatures. To determine the structural organization of HtrA, we have used electron microscopy and chemical cross-linking analysis. The averaged image of HtrA with end-on orientation revealed a six-membered, ring-shaped structure with a central cavity, and its side-on view showed a two-layered structure. Thus, HtrA behaves as a dodecamer consisting of two stacks of hexameric ring. HtrA can degrade thermally unfolded citrate synthase and malate dehydrogenase but cannot when in their native form. HtrA degraded partially unfolded casein more rapidly upon increasing the incubation temperature. However, it hydrolyzed oxidized insulin B-chain, which is fully unfolded, at nearly the same rate at all of the temperatures tested. HtrA also rapidly degraded reduced insulin B-chain generated by treatment of insulin with dithiothreitol but not A-chain or intact insulin. Moreover, HtrA degraded fully unfolded alpha-lactalbumin, of which all four disulfide bonds were reduced, but not the native alpha-lactalbumin and its unfolded intermediates containing two or three disulfide bonds. These results indicate that unfolding of the protein substrates, such as by exposure to high temperatures or reduction of disulfide bonds, is essential for their access into the inner chamber of the double ring-shaped HtrA, where cleavage of peptide bonds may occur. Thus, HtrA with a self-compartmentalizing structure may play an important role in elimination of unfolded proteins in the periplasm of Escherichia coli.
Collapse
Affiliation(s)
- K I Kim
- Department of Molecular Biology and Research Center for Cell Differentiation, College of Natural Sciences, Seoul National University, Seoul, 151-742, Korea
| | | | | | | | | |
Collapse
|
28
|
Akiyama Y. Self-processing of FtsH and its implication for the cleavage specificity of this protease. Biochemistry 1999; 38:11693-9. [PMID: 10512625 DOI: 10.1021/bi991177c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
FtsH, a membrane-bound and ATP-dependent protease of Escherichia coli, is involved in degradation of some of uncomplexed integral membrane proteins and short-lived cytoplasmic proteins. It is composed of an N-terminal membrane-spanning region and a following large cytoplasmic domain that contains ATPase and protease active sites. In the present study, it was found that FtsH undergoes C-terminal processing in vivo. The processing was blocked by loss of function mutations of FtsH. Purified FtsH-His(6)-Myc, a C-terminally tagged derivative of FtsH, was self-processed in vitro. This in vitro processing was observed only in the presence of ATP and not in the presence of adenosine 5'-(beta,gamma-imino)triphosphate (AMP-PNP). Moreover, such processing did not occur in the case of the ATPase motif mutant protein. These results indicated that this processing is a self-catalyzed reaction that needs ATP hydrolysis. Mutations in the hflKC genes that encode a possible modulator of FtsH, and the growth phase of the cells as well, affected the processing. Complementation experiments with genetically constructed variants suggested that both the processed and the unprocessed forms of FtsH are functional. The cleavage was found to occur between Met-640 and Ser-641, removing a heptapeptide from the C-terminus of FtsH. Systematic mutational analyses of Met-640 and Ser-641 revealed preferences for positively charged and hydrophobic amino acid residues at these positions for processing. This cleavage specificity may be shared by the self-cleavage and the substrate-cleavage reactions of this protease.
Collapse
Affiliation(s)
- Y Akiyama
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
| |
Collapse
|
29
|
Abstract
Escherichia coli FtsH degrades several integral membrane proteins, including YccA, having seven transmembrane segments, a cytosolic N-terminus and a periplasmic C-terminus. Evidence indicates that FtsH initiates proteolysis at the N-terminal cytosolic domain. SecY, having 10 transmembrane segments, is also a substrate of FtsH. We studied whether and how the FtsH-catalyzed proteolysis on the cytosolic side continues into the transmembrane and periplasmic regions using chimeric proteins, YccA-(P3)-PhoA-His6-Myc and SecY-(P5)-PhoA, with the alkaline phosphatase (PhoA) mature sequence in a periplasmic domain. The PhoA domain that was present within the fusion protein was rapidly degraded by FtsH when it lacked the DsbA-dependent folding. In contrast, both PhoA itself and the TM9-PhoA region of SecY-(P5)-PhoA were stable when expressed as independent polypeptides. In the presence of DsbA, the FtsH-dependent degradation stopped at a site near to the N-terminus of the PhoA moiety, leaving the PhoA domain (and its C-terminal region) undigested. The efficiency of this degradation stop correlated well with the rapidity of the folding of the PhoA domain. Thus, both transmembrane and periplasmic domains are degraded by the processive proteolysis by FtsH, provided they are not tightly folded. We propose that FtsH dislocates the extracytoplasmic domain of a substrate, probably using its ATPase activity.
Collapse
Affiliation(s)
- A Kihara
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | | | | |
Collapse
|
30
|
Spiess C, Beil A, Ehrmann M. A temperature-dependent switch from chaperone to protease in a widely conserved heat shock protein. Cell 1999; 97:339-47. [PMID: 10319814 DOI: 10.1016/s0092-8674(00)80743-6] [Citation(s) in RCA: 558] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Misfolding or unfolding of polypeptides can occur as a consequence of environmental stress and spontaneous mutation. The abundance of general chaperones and proteases suggests that cells distinguish between proteins that can be refolded and "hopeless" cases fated to enter the proteolytic pathway. The mechanisms controlling this key metabolic decision are not well understood. We show here that the widely conserved heat shock protein DegP (HtrA) has both general molecular chaperone and proteolytic activities. The chaperone function dominates at low temperatures, while the proteolytic activity is present at elevated temperatures. These results show that a single cellular factor can switch between two key pathways, controlling protein stability and turnover. Implications of this finding for intracellular protein metabolism are discussed.
Collapse
Affiliation(s)
- C Spiess
- Fakultät für Biologie, Universität Konstanz, Germany
| | | | | |
Collapse
|