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Devlin T, Fleming KG. A team of chaperones play to win in the bacterial periplasm. Trends Biochem Sci 2024; 49:667-680. [PMID: 38677921 DOI: 10.1016/j.tibs.2024.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/29/2024]
Abstract
The survival and virulence of Gram-negative bacteria require proper biogenesis and maintenance of the outer membrane (OM), which is densely packed with β-barrel OM proteins (OMPs). Before reaching the OM, precursor unfolded OMPs (uOMPs) must cross the whole cell envelope. A network of periplasmic chaperones and proteases maintains unfolded but folding-competent conformations of these membrane proteins in the aqueous periplasm while simultaneously preventing off-pathway aggregation. These periplasmic proteins utilize different strategies, including conformational heterogeneity, oligomerization, multivalency, and kinetic partitioning, to perform and regulate their functions. Redundant and unique characteristics of the individual periplasmic players synergize to create a protein quality control team capable responding to changing environmental stresses.
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Affiliation(s)
- Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
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2
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Li X, Zhou J, Han R, Yu F, Liu K, Zhao M, Liu Y, Xue Z, Zhao S. Phosphatase A1 accessory protein PlaS from Serratia marcescens controls cell membrane permeability, fluidity, hydrophobicity, and fatty acid composition in Escherichia coli BL21. Int J Biol Macromol 2023; 253:126776. [PMID: 37699461 DOI: 10.1016/j.ijbiomac.2023.126776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/28/2023] [Accepted: 09/05/2023] [Indexed: 09/14/2023]
Abstract
Phospholipase A1 (PlaA) plays a pivotal role in diverse applications within the food and biochemical medical industries. Herein, we investigate the impact of the accessory protein encoded by plaS from Serratia marcescens on PlaA activity in Escherichia coli. Notably, PlaS demonstrates the ability to enhance PlaA activity while concurrently exhibiting inhibitory effects on the growth of E. coli BL21 (DE3). Our study revolves around probing the inhibitory action of PlaS on E. coli BL21 (DE3). PlaS exhibits a propensity to heighten both the permeability of outer and inner cell membranes, leading to concomitant reductions in membrane fluidity and surface hydrophobicity. This phenomenon is validated through scanning electron microscopy (SEM) analysis, which highlights PlaS's capacity to compromise membrane integrity. Moreover, through a comprehensive comparative transcriptomic sequencing approach, we identify four down-regulated genes (galM, ybhC, ldtC, and kdpB) alongside two up-regulated genes (rbsB and degP). These genes are intricately associated with processes such as cell membrane synthesis and modification, energy metabolism, and transmembrane transport. Our investigation unveils the intricate gene-level mechanisms underpinning PlaS-mediated growth inhibition and membrane disruption. Consequently, our findings serve as a significant reference for the elucidation of membrane protein mechanisms, shedding light on potential avenues for future exploration.
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Affiliation(s)
- Xiangfei Li
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Jie Zhou
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Rumeng Han
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Fei Yu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Kun Liu
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Ming Zhao
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Yan Liu
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China
| | - Zhenglian Xue
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China.
| | - Shiguang Zhao
- Engineering Laboratory for Industrial Microbiology Molecular Beeding of Anhui Province, College of Biologic & Food Engineering, Anhui Polytechnic University, 8 Middle Beijing Road, Wuhu 241000, China.
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Proteolytic Activity of DegP Is Required for the Burkholderia Symbiont To Persist in Its Host Bean Bug. Microbiol Spectr 2023; 11:e0433022. [PMID: 36511662 PMCID: PMC9927360 DOI: 10.1128/spectrum.04330-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Symbiosis requires the adaptation of symbiotic bacteria to the host environment. Symbiotic factors for bacterial adaptation have been studied in various experimental models, including the Burkholderia-bean bug symbiosis model. Previously identified symbiotic factors of Burkholderia symbionts of bean bugs provided insight into the host environment being stressful to the symbionts. Because DegP, which functions as both a protease and a chaperone, supports bacterial growth under various stressful conditions, we hypothesized that DegP might be a novel symbiotic factor of Burkholderia symbionts in the symbiotic association with bean bugs. The expression level of degP was highly elevated in symbiotic Burkholderia cells in comparison with cultured cells. When the degP-deficient strain competed for symbiotic association against the wild-type strain, the ΔdegP strain showed no symbiotic competitiveness. In vivo monoinfection with the ΔdegP strain revealed a lower symbiont titer in the symbiotic organ than that of the wild-type strain, indicating that the ΔdegP strain failed to persist in the host. In in vitro assays, the ΔdegP strain showed susceptibility to heat and high-salt stressors and a decreased level of biofilm formation. To further determine the role of the proteolytic activity of DegP in symbiosis, we generated missense mutant DegPS248A exhibiting a defect in protease activity only. The ΔdegP strain complemented with degPS248A showed in vitro characteristics similar to those of the ΔdegP strain and failed to persist in the symbiotic organ. Together, the results of our study demonstrated that the proteolytic activity of DegP, which is involved in the stress resistance and biofilm formation of the Burkholderia symbiont, plays an essential role in symbiotic persistence in the host bean bug. IMPORTANCE Bacterial DegP has dual functions as a protease and a chaperone and supports bacterial growth under stressful conditions. In symbioses involving bacteria, bacterial symbionts encounter various stressors and may need functional DegP for symbiotic association with the host. Using the Burkholderia-bean bug symbiosis model, which is a useful model for identifying bacterial symbiotic factors, we demonstrated that DegP is indeed a symbiotic factor of Burkholderia persistence in its host bean bug. In vitro experiments to understand the symbiotic mechanisms of degP revealed that degP confers resistance to heat and high-salt stresses. In addition, degP supports biofilm formation, which is a previously identified persistence factor of the Burkholderia symbiont. Furthermore, using a missense mutation in a protease catalytic site of degP, we specifically elucidated that the proteolytic activity of degP plays essential roles in stress resistance, biofilm formation, and, thus, symbiotic persistence in the host bean bug.
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Šulskis D, Thoma J, Burmann BM. Structural basis of DegP protease temperature-dependent activation. SCIENCE ADVANCES 2021; 7:eabj1816. [PMID: 34878848 PMCID: PMC8654288 DOI: 10.1126/sciadv.abj1816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 10/16/2021] [Indexed: 05/21/2023]
Abstract
Protein quality control is an essential cellular function mainly executed by a vast array of different proteases and molecular chaperones. One of the bacterial high temperature requirement A (HtrA) protein family members, the homo-oligomeric DegP protease, plays a crucial role in the Escherichia coli protein quality control machinery by removing unfolded proteins or preventing their aggregation and chaperoning them to their final folded state within the periplasm. DegP contains two regulatory PDZ domains, which play key roles in substrate recognition and in the transformation of DegP between inactive hexameric and proteolytic active cage-like structures. Here, we analyze the interaction and dynamics of the DegP PDZ domains underlying this transformation by high-resolution NMR spectroscopy complemented with biochemical cleavage assays. We identify an interdomain molecular lock, which controls the interactions between the two PDZ domains, regulated by fine-tuned temperature-dependent protein dynamics, and which is potentially conserved in proteins harboring tandem PDZ domains.
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Affiliation(s)
- Darius Šulskis
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Göteborg, Sweden
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, 405 30 Göteborg, Sweden
| | - Johannes Thoma
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Göteborg, Sweden
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, 405 30 Göteborg, Sweden
| | - Björn M. Burmann
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Göteborg, Sweden
- Wallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, 405 30 Göteborg, Sweden
- Corresponding author.
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Kim H, Wu K, Lee C. Stress-Responsive Periplasmic Chaperones in Bacteria. Front Mol Biosci 2021; 8:678697. [PMID: 34046432 PMCID: PMC8144458 DOI: 10.3389/fmolb.2021.678697] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/19/2021] [Indexed: 01/14/2023] Open
Abstract
Periplasmic proteins are involved in a wide range of bacterial functions, including motility, biofilm formation, sensing environmental cues, and small-molecule transport. In addition, a wide range of outer membrane proteins and proteins that are secreted into the media must travel through the periplasm to reach their final destinations. Since the porous outer membrane allows for the free diffusion of small molecules, periplasmic proteins and those that travel through this compartment are more vulnerable to external environmental changes, including those that result in protein unfolding, than cytoplasmic proteins are. To enable bacterial survival under various stress conditions, a robust protein quality control system is required in the periplasm. In this review, we focus on several periplasmic chaperones that are stress responsive, including Spy, which responds to envelope-stress, DegP, which responds to temperature to modulate chaperone/protease activity, HdeA and HdeB, which respond to acid stress, and UgpB, which functions as a bile-responsive chaperone.
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Affiliation(s)
- Hyunhee Kim
- Department of Biological Sciences, Ajou University, Suwon, South Korea
- Molecular, Cellular, and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, United States
| | - Kevin Wu
- Molecular, Cellular, and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, United States
- Department of Biophysics, University of Michigan, Ann Arbor, MI, United States
| | - Changhan Lee
- Department of Biological Sciences, Ajou University, Suwon, South Korea
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Molecular mechanism of networking among DegP, Skp and SurA in periplasm for biogenesis of outer membrane proteins. Biochem J 2021; 477:2949-2965. [PMID: 32729902 DOI: 10.1042/bcj20200483] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/13/2022]
Abstract
The biogenesis of outer membrane proteins (OMPs) is an extremely challenging process. In the periplasm of Escherichia coli, a group of quality control factors work together to exercise the safe-guard and quality control of OMPs. DegP, Skp and SurA are the three most prominent ones. Although extensive investigations have been carried out, the molecular mechanism regarding the networking among these proteins remains mostly mysterious. Our group has previously studied the molecular interactions of OMPs with SurA and Skp, using single-molecule detection (SMD). In this work, again using SMD, we studied how OmpC, a representative of OMPs, interacts with DegP, Skp and SurA collectively. Several important discoveries were made. The self-oligomerization of DegP to form hexamer occurs over hundred micromolars. When OmpC is in a monomer state at a low concentration, the OmpC·DegP6 and OmpC·DegP24 complexes form when the DegP concentration is around sub-micromolars and a hundred micromolars, respectively. High OmpC concentration promotes the binding affinity of DegP to OmpC by ∼100 folds. Skp and SurA behave differently when they interact synergistically with DegP in the presence of substrate. DegP can degrade SurA-protected OmpC, but Skp-protected OmpC forms the ternary complex OmpC·(Skp3)n·DegP6 (n = 1,2) to resist the DegP-mediated degradation. Combined with previous results, we were able to depict a comprehensive picture regarding the molecular mechanism of the networking among DegP, Skp and SurA in the periplasm for the OMPs biogenesis under physiological and stressed conditions.
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Complex Response of the CpxAR Two-Component System to β-Lactams on Antibiotic Resistance and Envelope Homeostasis in Enterobacteriaceae. Antimicrob Agents Chemother 2020; 64:AAC.00291-20. [PMID: 32229490 DOI: 10.1128/aac.00291-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 03/17/2020] [Indexed: 01/17/2023] Open
Abstract
The Cpx stress response is widespread among Enterobacteriaceae We previously reported a mutation in cpxA in a multidrug-resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields a single-amino-acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxAY144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the effect of the intimate interconnection between the Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall-active antibiotic or by inactivating penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increases phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to cause abnormal accumulation of muropeptides (disaccharide-pentapeptide and N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycans caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular, the interaction between CpxA and CpxP, as a promising therapeutic target.
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Degp degrades a wide range of substrate proteins in Escherichia coli under stress conditions. Biochem J 2019; 476:3549-3564. [DOI: 10.1042/bcj20190446] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/05/2019] [Accepted: 11/18/2019] [Indexed: 11/17/2022]
Abstract
DegP, a periplasmic dual-functional protease and chaperone in Gram-negative bacteria, is critical for bacterial stress resistance, but the precise underlying mechanisms are not fully understood. Here, we show that the protease function of DegP is critical for Escherichia coli cells to maintain membrane integrity, particularly under heat shock conditions (42°C). Site-directed photo-cross-linking, mass spectrometry and immunoblotting analyses reveal that both periplasmic proteins (e.g. OppA and MalE) and β-barrel outer membrane proteins (OMPs) are DegP-interacting proteins and that OppA is degraded by DegP in vitro and in vivo at 42°C. In addition, OmpA and BamA, chimeric β-barrel OMPs containing a soluble periplasmic domain, are bound to DegP in both unfolded and folded forms, whereas only the unfolded forms are degradable by DegP. The presence of folded OmpA as a substrate of DegP is attributed to its periplasmic domain, which is resistant to DegP degradation and even generally protects pure β-barrel OMPs from degradation in an intra-molecular way. Furthermore, a pair of residues (R262 and V328) in the PDZ domain-1 of DegP play important roles for binding unfolded and folded β-barrel OMPs, with R262 being critical. Our study, together with earlier reports, indicates that DegP plays a critical role in protein quality control in the bacterial periplasm by degrading both periplasmic proteins and β-barrel OMPs under stress conditions and likely also by participating in the folding of chimeric β-barrel OMPs. A working model is proposed to illustrate the finely tuned functions of DegP with respect to different substrate proteins.
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Suppressor Mutations in degS Overcome the Acute Temperature-Sensitive Phenotype of Δ degP and Δ degP Δ tol-pal Mutants of Escherichia coli. J Bacteriol 2019; 201:JB.00742-18. [PMID: 30858298 DOI: 10.1128/jb.00742-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/25/2019] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, the periplasmic protease DegP plays a critical role in degrading misfolded outer membrane proteins (OMPs). Consequently, mutants lacking DegP display a temperature-sensitive growth defect, presumably due to the toxic accumulation of misfolded OMPs. The Tol-Pal complex plays a poorly defined but an important role in envelope biogenesis, since mutants defective in this complex display a classical periplasmic leakage phenotype. Double mutants lacking DegP and an intact Tol-Pal complex display exaggerated temperature-sensitive growth defects and the leaky phenotype. Two revertants that overcome the temperature-sensitive growth phenotype carry missense mutations in the degS gene, resulting in D102V and D320A substitutions. D320 and E317 of the PDZ domain of DegS make salt bridges with R178 of DegS's protease domain to keep the protease in the inactive state. However, weakening of the tripartite interactions by D320A increases DegS's basal protease activity. Although the D102V substitution is as effective as D320A in suppressing the temperature-sensitive growth phenotype, the molecular mechanism behind its effect on DegS's protease activity is unclear. Our data suggest that the two DegS variants modestly activate RseA-controlled, σE-mediated envelope stress response pathway and elevate periplasmic protease activity to restore envelope homeostasis. Based on the release of a cytoplasmic enzyme in the culture supernatant, we conclude that the conditional lethal phenotype of ΔtolB ΔdegP mutants stems from a grossly destabilized envelope structure that causes excessive cell lysis. Together, the data point to a critical role for periplasmic proteases when the Tol-Pal complex-mediated envelope structure and/or functions are compromised.IMPORTANCE The Tol-Pal complex plays a poorly defined role in envelope biogenesis. The data presented here show that DegP's periplasmic protease activity becomes crucial in mutants lacking the intact Tol-Pal complex, but this requirement can be circumvented by suppressor mutations that activate the basal protease activity of a regulatory protease, DegS. These observations point to a critical role for periplasmic proteases when Tol-Pal-mediated envelope structure and/or functions are perturbed.
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Abstract
The biogenesis of periplasmic and outer membrane proteins (OMPs) in Escherichia coli is assisted by a variety of processes that help with their folding and transport to their final destination in the cellular envelope. Chaperones are macromolecules, usually proteins, that facilitate the folding of proteins or prevent their aggregation without becoming part of the protein's final structure. Because chaperones often bind to folding intermediates, they often (but not always) act to slow protein folding. Protein folding catalysts, on the other hand, act to accelerate specific steps in the protein folding pathway, including disulfide bond formation and peptidyl prolyl isomerization. This review is primarily concerned with E. coli and Salmonella periplasmic and cellular envelope chaperones; it also discusses periplasmic proline isomerization.
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HtrA3 is a cellular partner of cytoskeleton proteins and TCP1α chaperonin. J Proteomics 2018; 177:88-111. [PMID: 29477555 DOI: 10.1016/j.jprot.2018.02.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 02/13/2018] [Accepted: 02/19/2018] [Indexed: 01/09/2023]
Abstract
The human HtrA3 protease is involved in placentation, mitochondrial homeostasis, stimulation of apoptosis and proposed to be a tumor suppressor. Molecular mechanisms of the HtrA3 functions are poorly understood and knowledge concerning its cellular targets is very limited. There are two HtrA3 isoforms, the long (HtrA3L) and short (HtrA3S). Upon stress, their N-terminal domains are removed, resulting in the more active ΔN-HtrA3. By pull down and mass spectrometry techniques, we identified a panel of putative ΔN-HtrA3L/S substrates. We confirmed that ΔN-HtrA3L/S formed complexes with actin, β-tubulin, vimentin and TCP1α in vitro and in a cell and partially co-localized with the actin and vimentin filaments, microtubules and TCP1α in a cell. In vitro, both isoforms cleaved the cytoskeleton proteins, promoted tubulin polymerization and displayed chaperone-like activity, with ΔN-HtrA3S being more efficient in proteolysis and ΔN-HtrA3L - in polymerization. TCP1α, essential for the actin and tubulin folding, was directly bound by the ΔN-HtrA3L/S but not cleaved. These results indicate that actin, β-tubulin, vimentin, and TCP1α are HtrA3 cellular partners and suggest that HtrA3 may influence cytoskeleton dynamics. They also suggest different roles of the HtrA3 isoforms and a possibility that HtrA3 protease may also function as a co-chaperone. SIGNIFICANCE The HtrA3 protease stimulates apoptosis and is proposed to be a tumor suppressor and a therapeutic target, however little is known about its function at the molecular level and very few HtrA3 physiological substrates have been identified so far. Furthermore, HtrA3 is the only member of the HtrA family of proteins which, apart from the long isoform possessing the PD and PDZ domains (HtrA3L), has a short isoform (HtrA3S) lacking the PDZ domain. In this work we identified a large panel (about 150) of the tentative HtrA3L/S cellular partners which provides a good basis for further research concerning the HtrA3 function. We have shown that the cytoskeleton proteins actin, β-tubulin and vimentin, and the TCP1α chaperonin are cellular partners of both HtrA3 isoforms. Our findings indicate that HtrA3 may promote destabilization of the actin and vimentin cytoskeleton and suggest that it may influence the dynamics of the microtubule network, with the HtrA3S being more efficient in cytoskeleton protein cleavage and HtrA3L - in tubulin polymerization. Also, we have shown for the first time that HtrA3 has a chaperone-like, holdase activity in vitro - activity typical for co-chaperone proteins. The proposed HtrA3 influence on the cytoskeleton dynamics may be one of the ways in which HtrA3 promotes cell death and affects cancerogenesis. We believe that the results of this study provide a new insight into the role of HtrA3 in a cell and further confirm the notion that HtrA3 should be considered as a target of new anti-cancer therapies.
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Hussain S, Bernstein HD. The Bam complex catalyzes efficient insertion of bacterial outer membrane proteins into membrane vesicles of variable lipid composition. J Biol Chem 2018; 293:2959-2973. [PMID: 29311257 DOI: 10.1074/jbc.ra117.000349] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/06/2017] [Indexed: 12/29/2022] Open
Abstract
Most proteins that reside in the bacterial outer membrane (OM) have a distinctive "β-barrel" architecture, but the assembly of these proteins is poorly understood. The spontaneous assembly of OM proteins (OMPs) into pure lipid vesicles has been studied extensively but often requires non-physiological conditions and time scales and is strongly influenced by properties of the lipid bilayer, including surface charge, thickness, and fluidity. Furthermore, the membrane insertion of OMPs in vivo is catalyzed by a heterooligomer called the β-barrel assembly machinery (Bam) complex. To determine the role of lipids in the assembly of OMPs under more physiological conditions, we exploited an assay in which the Bam complex mediates their insertion into membrane vesicles. After reconstituting the Bam complex into vesicles that contain a variety of different synthetic lipids, we found that two model OMPs, EspP and OmpA, folded efficiently regardless of the lipid composition. Most notably, both proteins folded into membranes composed of a gel-phase lipid that mimics the rigid bacterial OM. Interestingly, we found that EspP, OmpA, and another model protein (OmpG) folded at significantly different rates and that an α-helix embedded inside the EspP β-barrel accelerates folding. Our results show that the Bam complex largely overcomes effects that lipids exert on OMP assembly and suggest that specific interactions between the Bam complex and an OMP influence its rate of folding.
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Affiliation(s)
- Sunyia Hussain
- Genetics and Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0538
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0538.
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Zarzecka U, Modrak-Wojcik A, Bayassi M, Szewczyk M, Gieldon A, Lesner A, Koper T, Bzowska A, Sanguinetti M, Backert S, Lipinska B, Skorko-Glonek J. Biochemical properties of the HtrA homolog from bacterium Stenotrophomonas maltophilia. Int J Biol Macromol 2017; 109:992-1005. [PMID: 29155201 DOI: 10.1016/j.ijbiomac.2017.11.086] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/12/2017] [Accepted: 11/13/2017] [Indexed: 11/29/2022]
Abstract
The HtrA proteins due to their proteolytic, and in many cases chaperone activity, efficiently counteract consequences of stressful conditions. In the environmental bacterium and nosocomial pathogen Stenotrophomonas maltophilia HtrA (HtrASm) is induced as a part of adaptive response to host temperature (37°C). We examined the biochemical properties of HtrASm and compared them with those of model HtrAEc from Escherichia coli. We found that HtrASm is a protease and chaperone that operates over a wide range of pH and is highly active at temperatures between 35 and 37°C. The temperature-sensitive activity corresponded well with the lower thermal stability of the protein and weaker stability of the oligomer. Interestingly, the enzyme shows slightly different substrate cleavage specificity when compared to other bacterial HtrAs. A computational model of the three-dimensional structure of HtrASm indicates differences in the S1 substrate specificity pocket and suggests weaker inter-trimer interactions when compared to HtrAEc. The observed features of HtrASm suggest that this protein may play a protective role under stressful conditions acting both as a protease and a chaperone. The optimal temperatures for the protein activity may reflect the evolutionary adaptation of S. maltophilia to life in soil or aqueous environments, where the temperatures are usually much below 37°C.
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Affiliation(s)
- Urszula Zarzecka
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland
| | - Anna Modrak-Wojcik
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw 02-089, Poland
| | - Martyna Bayassi
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland
| | - Maciej Szewczyk
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland
| | - Artur Gieldon
- Department of Theoretical Chemistry, Faculty of Chemistry, University of Gdansk, Gdansk 80-952, Poland
| | - Adam Lesner
- Department of Molecular Biochemistry, Faculty of Chemistry, University of Gdansk, Gdansk 80-952, Poland
| | - Tomasz Koper
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland
| | - Agnieszka Bzowska
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw 02-089, Poland
| | - Maurizio Sanguinetti
- Institute of Microbiology, Catholic University of the Sacred Heart, Rome 00168, Italy
| | - Steffen Backert
- Division of Microbiology, Department of Biology, Friedrich Alexander University Erlangen-Nuremberg, Erlangen 91058, Germany
| | - Barbara Lipinska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland
| | - Joanna Skorko-Glonek
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Gdansk 80-308, Poland.
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Chang Z. The function of the DegP (HtrA) protein: Protease versus chaperone. IUBMB Life 2016; 68:904-907. [PMID: 27670951 DOI: 10.1002/iub.1561] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/06/2016] [Indexed: 11/06/2022]
Abstract
The DegP (or HtrA) is a highly conserved family of proteins functioning in all living organisms. It was initially identified as a protease functioning in the periplasmic space of the Gram-negative bacterial cells. It was later reported to also exhibit chaperone activity and thus has been designated as a bifunctional protein. However, recent studies demonstrated that in living cells it more likely functions only as a protease with hardly detectable chaperone activities. In this review, I will summarize the evidences clarifying that DegP more likely only functions as a protease rather than as a chaperone in cells. © 2016 IUBMB Life, 68(11):904-907, 2016.
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Affiliation(s)
- Zengyi Chang
- Center for Protein Science, State Key Laboratory of Protein and Plant Gene Studies, School of Life Sciences, Center for History and Philosophy of Science, Peking University, Beijing, China.
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15
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Braselmann E, Chaney JL, Champion MM, Clark PL. DegP Chaperone Suppresses Toxic Inner Membrane Translocation Intermediates. PLoS One 2016; 11:e0162922. [PMID: 27626276 PMCID: PMC5023192 DOI: 10.1371/journal.pone.0162922] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/30/2016] [Indexed: 11/18/2022] Open
Abstract
The periplasm of Gram-negative bacteria includes a variety of molecular chaperones that shepherd the folding and targeting of secreted proteins. A central player of this quality control network is DegP, a protease also suggested to have a chaperone function. We serendipitously discovered that production of the Bordetella pertussis autotransporter virulence protein pertactin is lethal in Escherichia coli ΔdegP strains. We investigated specific contributions of DegP to secretion of pertactin as a model system to test the functions of DegP in vivo. The DegP chaperone activity was sufficient to restore growth during pertactin production. This chaperone dependency could be relieved by changing the pertactin signal sequence: an E. coli signal sequence leading to co-translational inner membrane (IM) translocation was sufficient to suppress lethality in the absence of DegP, whereas an E. coli post-translational signal sequence was sufficient to recapitulate the lethal phenotype. These results identify a novel connection between the DegP chaperone and the mechanism used to translocate a protein across the IM. Lethality coincided with loss of periplasmic proteins, soluble σE, and proteins regulated by this essential stress response. These results suggest post-translational IM translocation can lead to the formation of toxic periplasmic folding intermediates, which DegP can suppress.
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Affiliation(s)
- Esther Braselmann
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
| | - Julie L. Chaney
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Matthew M. Champion
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Patricia L. Clark
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
- Department of Chemical & Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana, United States of America
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16
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Fan D, Liu C, Liu L, Zhu L, Peng F, Zhou Q. Large-scale gene expression profiling reveals physiological response to deletion of chaperone dnaKJ in Escherichia coli. Microbiol Res 2016; 186-187:27-36. [PMID: 27242140 DOI: 10.1016/j.micres.2016.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/28/2016] [Accepted: 03/03/2016] [Indexed: 11/18/2022]
Abstract
Chaperone DnaK and its co-chaperone DnaJ plays various essential roles such as in assisting in the folding of nascent peptides, preventing protein aggregation and maintaining cellular protein homeostasis. Global transcriptional changes in vivo associated with deletion of dnaKJ were monitored using DNA microarray to elucidate the role of DnaKJ at the transcriptional level. Microarray profiling and bioinformatics analysis revealed that a few chaperone and protease genes, stress-related genes and genes involved in the tricarboxylic acid cycle and oxidative phosphorylation were up-regulated, whereas various transporter genes, pentose phosphate pathway and transcriptional regulation related genes were down-regulated. This study is the first to systematically analyze the alterations at the transcriptional level in vivo in deletion of dnaKJ. Fatty acid methyl esters analysis indicated that the amount of unsaturated fatty acid sharply increased and subcellular location prediction analysis showed a marked decrease in transcription of inner-membrane protein genes, which might have triggered the development of aberrant cell shape and susceptibility for some antibiotics in the ΔdnaKJ strain.
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Affiliation(s)
- Dongjie Fan
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
| | - Chuanpeng Liu
- School of Life Science and Technology, Harbin Institute of Technology, 2 Yikuang Street, Harbin 150080, China.
| | - Lushan Liu
- Department of Emergency, Beijing Bo'ai Hospital, 10 Jiaomen North Road, Fengtai District, Beijing, 100068, China; China Rehabilitation Research Center, Capital Medical University, Beijing 100068, China
| | - Lingxiang Zhu
- National Research Institute for Family Planning (NRIFP), Beijing 100081, China
| | - Fang Peng
- China Center for Type Culture Collection (CCTCC), College of Life Sciences, Wuhan University, Wuhan430072, China; Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan 430072, China
| | - Qiming Zhou
- School of Life Science and Technology, Harbin Institute of Technology, 2 Yikuang Street, Harbin 150080, China.
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17
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Abstract
The major class of integral proteins found in the outer membrane (OM) of E. coli and Salmonella adopt a β-barrel conformation (OMPs). OMPs are synthesized in the cytoplasm with a typical signal sequence at the amino terminus, which directs them to the secretion machinery (SecYEG) located in the inner membrane for translocation to the periplasm. Chaperones such as SurA, or DegP and Skp, escort these proteins across the aqueous periplasm protecting them from aggregation. The chaperones then deliver OMPs to a highly conserved outer membrane assembly site termed the Bam complex. In E. coli, the Bam complex is composed of an essential OMP, BamA, and four associated OM lipoproteins, BamBCDE, one of which, BamD, is also essential. Here we provide an overview of what we know about the process of OMP assembly and outline the various hypotheses that have been proposed to explain how proteins might be integrated into the asymmetric OM lipid bilayer in an environment that lacks obvious energy sources. In addition, we describe the envelope stress responses that ensure the fidelity of OM biogenesis and how factors, such as phage and certain toxins, have coopted this essential machine to gain entry into the cell.
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18
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Ge X, Wang R, Ma J, Liu Y, Ezemaduka AN, Chen PR, Fu X, Chang Z. DegP primarily functions as a protease for the biogenesis of β-barrel outer membrane proteins in the Gram-negative bacterium Escherichia coli. FEBS J 2014; 281:1226-40. [PMID: 24373465 DOI: 10.1111/febs.12701] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/16/2013] [Accepted: 12/17/2013] [Indexed: 12/31/2022]
Abstract
DegP (also designated as HtrA) and its homologs are found in prokaryotic cells and such eukaryotic organelles as mitochondria and chloroplasts. DegP has been found to be essential for the growth of Gram-negative bacteria under heat shock conditions and arguably considered to possess both protease and chaperone activities. The function of DegP has not been clearly defined. Using genetically incorporated non-natural amino acids as photo-crosslinkers, here we identified the β-barrel outer membrane proteins (OMPs) as the major natural substrates of DegP in Escherichia coli cells. We also demonstrated that DegP primarily functions as a protease, at both low and high temperatures, to eliminate unfolded OMPs, with hardly any appreciable chaperone activity in cells. We also found that the toxic and cell membrane-damaging misfolded OMPs would accumulate in DegP-lacking cells cultured under heat shock conditions. Together, our study defines the primary function of DegP in OMP biogenesis and offers a mechanistic insight into the essentiality of DegP for cell growth under heat shock conditions.
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Affiliation(s)
- Xi Ge
- State Key Laboratory of Protein and Plant Gene Research and School of Life Sciences, Peking University, China
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19
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Identification of FkpA as a key quality control factor for the biogenesis of outer membrane proteins under heat shock conditions. J Bacteriol 2013; 196:672-80. [PMID: 24272780 DOI: 10.1128/jb.01069-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane proteins (OMPs) of Gram-negative bacterial cells, as well as the mitochondrion and chloroplast organelles, possess unique and highly stable β-barrel structures. Biogenesis of OMPs in Escherichia coli involves such periplasmic chaperones as SurA and Skp. In this study, we found that the ΔsurA Δskp double-deletion strain of E. coli, although lethal and defective in the biogenesis of OMPs at the normal growth temperature, is viable and effective at the heat shock temperature. We identified FkpA as the multicopy suppressor for the lethal phenotype of the ΔsurA Δskp strain. We also demonstrated that the deletion of fkpA from the ΔsurA cells resulted in only a mild decrease in the levels of folded OMPs at the normal temperature but a severe decrease as well as lethality at the heat shock temperature, whereas the deletion of fkpA from the Δskp cells had no detectable effect on OMP biogenesis at either temperature. These results strongly suggest a functional redundancy between FkpA and SurA for OMP biogenesis under heat shock stress conditions. Mechanistically, we found that FkpA becomes a more efficient chaperone for OMPs under the heat shock condition, with increases in both binding rate and affinity. In light of these observations and earlier reports, we propose a temperature-responsive OMP biogenesis mechanism in which the degrees of functional importance of the three chaperones are such that SurA > Skp > FkpA at the normal temperature but FkpA ≥ SurA > Skp at the heat shock temperature.
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Protease homolog BepA (YfgC) promotes assembly and degradation of β-barrel membrane proteins in Escherichia coli. Proc Natl Acad Sci U S A 2013; 110:E3612-21. [PMID: 24003122 DOI: 10.1073/pnas.1312012110] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Gram-negative bacteria are equipped with quality-control systems for the outer membrane (OM) that sense and cope with defective biogenesis of its components. Accumulation of misfolded outer membrane proteins (OMPs) in Escherichia coli leads to activation of σ(E), an essential alternative σ factor that up-regulates transcription of multiple genes required to preserve OM structure and function. Disruption of bepA (formerly yfgC), a σ(E)-regulated gene encoding a putative periplasmic metalloprotease, sensitizes cells to multiple drugs, suggesting that it may be involved in maintaining OM integrity. However, the specific function of BepA remains unclear. Here, we show that BepA enhances biogenesis of LptD, an essential OMP involved in OM transport and assembly of lipopolysaccharide, by promoting rearrangement of intramolecular disulfide bonds of LptD. In addition, BepA possesses protease activity and is responsible for the degradation of incorrectly folded LptD. In the absence of periplasmic chaperone SurA, BepA also promotes degradation of BamA, the central OMP subunit of the β-barrel assembly machinery (BAM) complex. Interestingly, defective oxidative folding of LptD caused by bepA disruption was partially suppressed by expression of protease-active site mutants of BepA, suggesting that BepA functions independently of its protease activity. We also show that BepA has genetic and physical interaction with components of the BAM complex. These findings raised the possibility that BepA maintains the integrity of OM both by promoting assembly of OMPs and by proteolytically eliminating OMPs when their correct assembly was compromised.
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21
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Cage assembly of DegP protease is not required for substrate-dependent regulation of proteolytic activity or high-temperature cell survival. Proc Natl Acad Sci U S A 2012; 109:7263-8. [PMID: 22529381 DOI: 10.1073/pnas.1204791109] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DegP, a member of the highly conserved HtrA family, performs quality-control degradation of misfolded proteins in the periplasm of gram-negative bacteria and is required for high-temperature survival of Escherichia coli. Substrate binding transforms DegP from an inactive oligomer containing two trimers into active polyhedral cages, typically containing four or eight trimers. Although these observations suggest a causal connection, we show that cage assembly and proteolytic activation can be uncoupled. Indeed, DegP variants that remain trimeric, hexameric, or dodecameric in the presence or absence of substrate still display robust and positively cooperative substrate degradation in vitro and, most importantly, sustain high-temperature bacterial growth as well as the wild-type enzyme. Our results support a model in which substrate binding converts inactive trimers into proteolytically active trimers, and simultaneously leads to cage assembly by enhancing binding of PDZ1 domains in one trimer to PDZ2' domains in neighboring trimers. Thus, both processes depend on substrate binding, but they can be uncoupled without loss of biological function. We discuss potential coupling mechanisms and why cage formation may have evolved if it is not required for DegP proteolysis.
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22
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Reversal of the ΔdegP phenotypes by a novel rpoE allele of Escherichia coli. PLoS One 2012; 7:e33979. [PMID: 22439016 PMCID: PMC3306311 DOI: 10.1371/journal.pone.0033979] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/20/2012] [Indexed: 11/20/2022] Open
Abstract
RseA sequesters RpoE (σE) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σE to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σE regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σE levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σE-dependent RybB::LacZ construct showed only a weak activation of the σE pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σE and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrAL222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σE-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σE-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σE may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σE levels.
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23
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The translocation domain in trimeric autotransporter adhesins is necessary and sufficient for trimerization and autotransportation. J Bacteriol 2011; 194:827-38. [PMID: 22155776 DOI: 10.1128/jb.05322-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Trimeric autotransporter adhesins (TAAs) comprise one of the secretion pathways of the type V secretion system. The mechanism of their translocation across the outer membrane remains unclear, but it most probably occurs by the formation of a hairpin inside the β-barrel translocation unit, leading to transportation of the passenger domain from the C terminus to the N terminus through the lumen of the β-barrel. We further investigated the phenomenon of autotransportation and the rules that govern it. We showed by coexpressing different Escherichia coli immunoglobulin-binding (Eib) proteins that highly similar TAAs could form stochastically mixed structures (heterotrimers). We further investigated this phenomenon by coexpressing two more distantly related TAAs, EibA and YadA. These, however, did not form heterotrimers; indeed, coexpression was lethal to the cells, leading to elimination of one or another of the genes. However, substituting in either protein the barrel of the other one so that the barrels were identical led to formation of heterotrimers as for Eibs. Our work shows that trimerization of the β-barrel, but not the passenger domain, is necessary and sufficient for TAA secretion while the passenger domain is not.
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24
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Interaction between bacterial outer membrane proteins and periplasmic quality control factors: a kinetic partitioning mechanism. Biochem J 2011; 438:505-11. [PMID: 21671888 DOI: 10.1042/bj20110264] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The OMPs (outer membrane proteins) of Gram-negative bacteria have to be translocated through the periplasmic space before reaching their final destination. The aqueous environment of the periplasmic space and high permeability of the outer membrane engender such a translocation process inevitably challenging. In Escherichia coli, although SurA, Skp and DegP have been identified to function in translocating OMPs across the periplasm, their precise roles and their relationship remain to be elucidated. In the present paper, by using fluorescence resonance energy transfer and single-molecule detection, we have studied the interaction between the OMP OmpC and these periplasmic quality control factors. The results of the present study reveal that the binding rate of OmpC to SurA or Skp is much faster than that to DegP, which may lead to sequential interaction between OMPs and different quality control factors. Such a kinetic partitioning mechanism for the chaperone-substrate interaction may be essential for the quality control of the biogenesis of OMPs.
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25
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Unique residues involved in activation of the multitasking protease/chaperone HtrA from Chlamydia trachomatis. PLoS One 2011; 6:e24547. [PMID: 21931748 PMCID: PMC3169616 DOI: 10.1371/journal.pone.0024547] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 08/12/2011] [Indexed: 11/19/2022] Open
Abstract
DegP, a member of the HtrA family of proteins, conducts critical bacterial protein quality control by both chaperone and proteolysis activities. The regulatory mechanisms controlling these two distinct activities, however, are unknown. DegP activation is known to involve a unique mechanism of allosteric binding, conformational changes and oligomer formation. We have uncovered a novel role for the residues at the PDZ1:protease interface in oligomer formation specifically for chaperone substrates of Chlamydia trachomatis HtrA (DegP homolog). We have demonstrated that CtHtrA proteolysis could be activated by allosteric binding and oligomer formation. The PDZ1 activator cleft was required for the activation and oligomer formation. However, unique to CtHtrA was the critical role for residues at the PDZ1:protease interface in oligomer formation when the activator was an in vitro chaperone substrate. Furthermore, a potential in vivo chaperone substrate, the major outer membrane protein (MOMP) from Chlamydia, was able to activate CtHtrA and induce oligomer formation. Therefore, we have revealed novel residues involved in the activation of CtHtrA which are likely to have important in vivo implications for outer membrane protein assembly.
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26
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Ricci DP, Silhavy TJ. The Bam machine: a molecular cooper. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1067-84. [PMID: 21893027 DOI: 10.1016/j.bbamem.2011.08.020] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 08/08/2011] [Accepted: 08/15/2011] [Indexed: 11/24/2022]
Abstract
The bacterial outer membrane (OM) is an exceptional biological structure with a unique composition that contributes significantly to the resiliency of Gram-negative bacteria. Since all OM components are synthesized in the cytosol, the cell must efficiently transport OM-specific lipids and proteins across the cell envelope and stably integrate them into a growing membrane. In this review, we discuss the challenges associated with these processes and detail the elegant solutions that cells have evolved to address the topological problem of OM biogenesis. Special attention will be paid to the Bam machine, a highly conserved multiprotein complex that facilitates OM β-barrel folding. This article is part of a Special Issue entitled: Protein Folding in Membranes.
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Affiliation(s)
- Dante P Ricci
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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27
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Iwanczyk J, Leong V, Ortega J. Factors defining the functional oligomeric state of Escherichia coli DegP protease. PLoS One 2011; 6:e18944. [PMID: 21526129 PMCID: PMC3081313 DOI: 10.1371/journal.pone.0018944] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/24/2011] [Indexed: 12/04/2022] Open
Abstract
Escherichia coli DegP protein is a periplasmic protein that functions both as a protease and as a chaperone. In the absence of substrate, DegP oligomerizes as a hexameric cage but in its presence DegP reorganizes into 12 and 24-mer cages with large chambers that house the substrate for degradation or refolding. Here, we studied the factors that determine the oligomeric state adopted by DegP in the presence of substrate. Using size exclusion chromatography and electron microscopy, we found that the size of the substrate molecule is the main factor conditioning the oligomeric state adopted by the enzyme. Other factors such as temperature, a major regulatory factor of the activity of this enzyme, did not influence the oligomeric state adopted by DegP. In addition, we observed that substrate concentration exerted an effect only when large substrates (full-length proteins) were used. However, small substrate molecules (peptides) always triggered the same oligomeric state regardless of their concentration. These results clarify important aspects of the regulation of the oligomeric state of DegP.
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Affiliation(s)
- Jack Iwanczyk
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Vivian Leong
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
| | - Joaquin Ortega
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario, Canada
- * E-mail:
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28
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Bennion D, Charlson ES, Coon E, Misra R. Dissection of β-barrel outer membrane protein assembly pathways through characterizing BamA POTRA 1 mutants of Escherichia coli. Mol Microbiol 2011; 77:1153-71. [PMID: 20598079 DOI: 10.1111/j.1365-2958.2010.07280.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BamA of Escherichia coli is an essential component of the hetero-oligomeric machinery that mediates β-barrel outer membrane protein (OMP) assembly. The C- and N-termini of BamA fold into trans-membrane β-barrel and five soluble POTRA domains respectively. Detailed characterization of BamA POTRA 1 missense and deletion mutants revealed two competing OMP assembly pathways, one of which is followed by the archetypal trimeric β-barrel OMPs, OmpF and LamB, and is dependent on POTRA 1. Interestingly, our data suggest that BamA also requires its POTRA 1 domain for proper assembly. The second pathway is independent of POTRA 1 and is exemplified by TolC. Site-specific cross-linking analysis revealed that the POTRA 1 domain of BamA interacts with SurA, a periplasmic chaperone required for the assembly of OmpF and LamB, but not that of TolC and BamA. The data suggest that SurA and BamA POTRA 1 domain function in concert to assist folding and assembly of most β-barrel OMPs except for TolC, which folds into a unique soluble α-helical barrel and an OM-anchored β-barrel. The two assembly pathways finally merge at some step beyond POTRA 1 but presumably before membrane insertion, which is thought to be catalysed by the trans-membrane β-barrel domain of BamA.
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Affiliation(s)
- Drew Bennion
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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29
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Involvement of the Shewanella oneidensis decaheme cytochrome MtrA in the periplasmic stability of the beta-barrel protein MtrB. Appl Environ Microbiol 2010; 77:1520-3. [PMID: 21169449 DOI: 10.1128/aem.01201-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Shewanella oneidensis outer membrane β-barrel protein MtrB is part of a membrane-spanning protein complex (MtrABC) which is necessary for dissimilatory iron reduction. Quantitative PCR, heterologous gene expression, and mutant studies indicated that MtrA is required for periplasmic stability of MtrB. DegP depletion compensated for this MtrA dependence.
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30
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Gerken H, Leiser OP, Bennion D, Misra R. Involvement and necessity of the Cpx regulon in the event of aberrant beta-barrel outer membrane protein assembly. Mol Microbiol 2010; 75:1033-46. [PMID: 20487295 DOI: 10.1111/j.1365-2958.2009.07042.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Cpx and sigma(E) regulons help maintain outer membrane integrity; the Cpx pathway monitors the biogenesis of cell surface structures, such as pili, while the sigma(E) pathway monitors the biogenesis of beta-barrel outer membrane proteins (OMPs). In this study we revealed the importance of the Cpx regulon in the event of beta-barrel OMP mis-assembly, by utilizing mutants expressing either a defective beta-barrel OMP assembly machinery (Bam) or assembly defective beta-barrel OMPs. Analysis of specific mRNAs showed that Delta cpxR bam double mutants failed to induce degP expression beyond the wild type level, despite activation of the sigma(E) pathway. The synthetic conditional lethal phenotype of Delta cpxR in mutant Bam or beta-barrel OMP backgrounds was reversed by wild type DegP expressed from a heterologous plasmid promoter. Consistent with the involvement of the Cpx regulon in the event of aberrant beta-barrel OMP assembly, the expression of cpxP, the archetypal member of the cpx regulon, was upregulated in defective Bam backgrounds or in cells expressing a single assembly-defective beta-barrel OMP species. Together, these results showed that both the Cpx and sigma(E) regulons are required to reduce envelope stress caused by aberrant beta-barrel OMP assembly, with the Cpx regulon principally contributing by controlling degP expression.
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Affiliation(s)
- Henri Gerken
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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31
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Allen WJ, Phan G, Waksman G. Structural biology of periplasmic chaperones. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2009; 78:51-97. [PMID: 20663484 DOI: 10.1016/s1876-1623(08)78003-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Proteins often require specific helper proteins, chaperones, to assist with their correct folding and to protect them from denaturation and aggregation. The cell envelope of Gram-negative bacteria provides a particularly challenging environment for chaperones to function in as it lacks readily available energy sources such as adenosine 5' triphosphate (ATP) to power reaction cycles. Periplasmic chaperones have therefore evolved specialized mechanisms to carry out their functions without the input of external energy and in many cases to transduce energy provided by protein folding or ATP hydrolysis at the inner membrane. Structural and biochemical studies have in recent years begun to elucidate the specific functions of many important periplasmic chaperones and how these functions are carried out. This includes not only specific carrier chaperones, such as those involved in the biosynthesis of adhesive fimbriae in pathogenic bacteria, but also more general pathways including the periplasmic transport of outer membrane proteins and the extracytoplasmic stress responses. This chapter aims to provide an overview of protein chaperones so far identified in the periplasm and how structural biology has assisted with the elucidation of their functions.
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Affiliation(s)
- William J Allen
- Institute of Structural and Molecular Biology, Birkbeck and University College London, London WC1E 7HX, UK
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Walther DM, Rapaport D, Tommassen J. Biogenesis of beta-barrel membrane proteins in bacteria and eukaryotes: evolutionary conservation and divergence. Cell Mol Life Sci 2009; 66:2789-804. [PMID: 19399587 PMCID: PMC2724633 DOI: 10.1007/s00018-009-0029-z] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 03/26/2009] [Accepted: 04/01/2009] [Indexed: 01/01/2023]
Abstract
Membrane-embedded beta-barrel proteins span the membrane via multiple amphipathic beta-strands arranged in a cylindrical shape. These proteins are found in the outer membranes of Gram-negative bacteria, mitochondria and chloroplasts. This situation is thought to reflect the evolutionary origin of mitochondria and chloroplasts from Gram-negative bacterial endosymbionts. beta-barrel proteins fulfil a variety of functions; among them are pore-forming proteins that allow the flux of metabolites across the membrane by passive diffusion, active transporters of siderophores, enzymes, structural proteins, and proteins that mediate protein translocation across or insertion into membranes. The biogenesis process of these proteins combines evolutionary conservation of the central elements with some noticeable differences in signals and machineries. This review summarizes our current knowledge of the functions and biogenesis of this special family of proteins.
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Affiliation(s)
- Dirk M. Walther
- Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
- Department of Proteomics and Signal Transduction, Max-Planck-Institute of Biochemistry, 82152 Martinsried, Germany
| | - Doron Rapaport
- Interfaculty Institute for Biochemistry, University of Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany
| | - Jan Tommassen
- Department of Molecular Microbiology, Institute of Biomembranes, Utrecht University, 3584 CH Utrecht, The Netherlands
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Baud C, Hodak H, Willery E, Drobecq H, Locht C, Jamin M, Jacob-Dubuisson F. Role of DegP for two-partner secretion in Bordetella. Mol Microbiol 2009; 74:315-29. [PMID: 19703106 DOI: 10.1111/j.1365-2958.2009.06860.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sorting of proteins destined to the surface or the extracellular milieu is mediated by specific machineries, which guide the protein substrates towards the proper route of secretion and determine the compartment in which folding occurs. In gram-negative bacteria, the two-partner secretion (TPS) pathway is dedicated to the secretion of large proteins rich in beta-helical structure. The secretion of the filamentous haemagglutinin (FHA), a 230 kDa adhesin of Bordetella pertussis, represents a model TPS system. FHA is exported by the Sec machinery and transits through the periplasm in an extended conformation. From there it is translocated across the outer membrane by its dedicated transporter FhaC to finally fold into a long beta-helix at the cell surface in a progressive manner. In this work, we show that B. pertussis lacking the periplasmic chaperone/protease DegP has a strong growth defect at 37 degrees C, and the integrity of its outer membrane is compromised. While both phenotypes are significantly aggravated by the presence of FHA, the chaperone activity of DegP markedly alleviates the periplasmic stress. In vitro, DegP binds to non-native FHA with high affinity. We propose that DegP chaperones the extended FHA polypeptide in the periplasm and is thus involved in the TPS pathway.
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Affiliation(s)
- C Baud
- INSERM U629, Lille, France
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Gerken H, Charlson ES, Cicirelli EM, Kenney LJ, Misra R. MzrA: a novel modulator of the EnvZ/OmpR two-component regulon. Mol Microbiol 2009; 72:1408-22. [PMID: 19432797 PMCID: PMC2727453 DOI: 10.1111/j.1365-2958.2009.06728.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Analysis of suppressors that alleviate the acute envelope stress phenotype of a ΔbamBΔdegP strain of Escherichia coli identified a novel protein MzrA and pleiotropic envZ mutations. Genetic evidence shows that overexpression of MzrA – formerly known as YqjB and EcfM – modulates the activity of EnvZ/OmpR similarly to pleiotropic EnvZ mutants and alter porin expression. However, porin expression in strains devoid of MzrA or overexpressing it is still sensitive to medium osmolarity, pH and procaine, all of which modulate EnvZ/OmpR activities. Thus, MzrA appears to alter the output of the EnvZ/OmpR system but not its ability to receive and respond to various environmental signals. Localization and topology experiments indicate that MzrA is a type II membrane protein, with its N-terminus exposed in the cytoplasm and C-terminus in the periplasm. Bacterial two-hybrid experiments determined that MzrA specifically interacts with EnvZ but not with OmpR or the related membrane sensor kinase, CpxA. This and additional genetic and biochemical evidence suggest that the interaction of MzrA with EnvZ would either enhance EnvZ's kinase activity or reduce its phosphatase activity, thus elevating the steady state levels of OmpR∼P. Furthermore, our data show that MzrA links the two-component envelope stress response regulators, CpxA/CpxR and EnvZ/OmpR.
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Affiliation(s)
- Henri Gerken
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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Lewis C, Skovierova H, Rowley G, Rezuchova B, Homerova D, Stevenson A, Spencer J, Farn J, Kormanec J, Roberts M. Salmonella enterica Serovar Typhimurium HtrA: regulation of expression and role of the chaperone and protease activities during infection. MICROBIOLOGY-SGM 2009; 155:873-881. [PMID: 19246758 DOI: 10.1099/mic.0.023754-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
HtrA is a bifunctional stress protein required by many bacterial pathogens to successfully cause infection. Salmonella enterica serovar Typhimurium (S. Typhimurium) htrA mutants are defective in intramacrophage survival and are highly attenuated in mice. Transcription of htrA in Escherichia coli is governed by a single promoter that is dependent on sigma(E) (RpoE). S. Typhimurium htrA also possesses a sigma(E)-dependent promoter; however, we found that the absence of sigma(E) had little effect on production of HtrA by S. Typhimurium. This suggests that additional promoters control expression of htrA in S. Typhimurium. We identified three S. Typhimurium htrA promoters. Only the most proximal promoter, htrAp3, was sigma(E) dependent. The other promoters, htrAp1 and htrAp2, are probably recognized by the principal sigma factor sigma(70). These two promoters were constitutively expressed but were also slightly induced by heat shock. Thus expression of htrA is different in S. Typhimurium and E. coli. The role of HtrA is to deal with misfolded/damaged proteins in the periplasm. It can do this either by degrading (protease activity) or folding/capturing (chaperone/sequestering, C/S, activity) the aberrant protein. We investigated which of these functions are important to S. Typhimurium in vitro and in vivo. Point or deletion mutants of htrA that encode variant HtrA molecules have been used in previous studies to investigate the role of different regions of HtrA in C/S and protease activity. These htrA variants were placed under the control of the S. Typhimurium htrAP123 promoters and expressed in a S. Typhimurium htrA mutant, GVB1343. Both wild-type HtrA and HtrA (HtrA S210A) lacking protease activity enabled GVB1343 to grow at high temperature (46 degrees C). Both molecules also significantly enhanced the growth/survival of GVB1343 in the liver and spleen of mice during infection. However, expression of wild-type HtrA enabled GVB1343 to grow to much higher levels than expression of HtrA S210A. Thus both the protease and C/S functions of HtrA operate in vivo during infection but the protease function is probably more important. Absence of either PDZ domain completely abolished the ability of HtrA to complement the growth defects of GVB1343 in vitro or in vivo.
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Affiliation(s)
- Claire Lewis
- Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Henrieta Skovierova
- Institute of Molecular Biology, Slovak Academy of Science, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Bronislava Rezuchova
- Institute of Molecular Biology, Slovak Academy of Science, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik
| | - Dagmar Homerova
- Institute of Molecular Biology, Slovak Academy of Science, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik
| | - Andrew Stevenson
- Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Janice Spencer
- Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Jacinta Farn
- Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Jan Kormanec
- Institute of Molecular Biology, Slovak Academy of Science, Dubravska cesta 21, 845 51 Bratislava, Slovak Republik
| | - Mark Roberts
- Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
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Bowl-shaped oligomeric structures on membranes as DegP's new functional forms in protein quality control. Proc Natl Acad Sci U S A 2009; 106:4858-63. [PMID: 19255437 DOI: 10.1073/pnas.0811780106] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the periplasm of Escherichia coli, DegP (also known as HtrA), which has both chaperone-like and proteolytic activities, prevents the accumulation of toxic misfolded and unfolded polypeptides. In solution, upon binding to denatured proteins, DegP forms large cage-like structures. Here, we show that DegP forms a range of bowl-shaped structures, independent of substrate proteins, each with a 4-, 5-, or 6-fold symmetry and all with a DegP trimer as the structural unit, on lipid membranes. These membrane-bound DegP assemblies have the capacity to recruit and process substrates in the bowl chamber, and they exhibit higher proteolytic and lower chaperone-like activities than DegP in solution. Our findings imply that DegP might regulate its dual roles during protein quality control, depending on its assembly state in the narrow bacterial envelope.
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Skorko-Glonek J, Sobiecka-Szkatula A, Narkiewicz J, Lipinska B. The proteolytic activity of the HtrA (DegP) protein from Escherichia coli at low temperatures. MICROBIOLOGY-SGM 2009; 154:3649-3658. [PMID: 19047732 DOI: 10.1099/mic.0.2008/020487-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The HtrA (DegP) protein from Escherichia coli is a periplasmic protease whose function is to protect cells from the deleterious effects of various stress conditions. At temperatures below 28 degrees C the proteolytic activity of HtrA was regarded as negligible and it was believed that the protein mainly plays the role of a chaperone. In the present work we provide evidence that HtrA can in fact act as a protease at low temperatures. Under folding stress, caused by disturbances in the disulfide bond formation, the lack of proteolytic activity of HtrA lowered the survival rates of mutant strains deprived of a functional DsbA/DsbB oxidoreductase system. HtrA degraded efficiently the unfolded, reduced alkaline phosphatase at 20 degrees C, both in vivo and in vitro. The cleavage was most efficient in the case of HtrA deprived of its internal S-S bond; therefore we expect that the reduction of HtrA may play a regulatory role in proteolysis.
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Affiliation(s)
- Joanna Skorko-Glonek
- University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland
| | | | - Joanna Narkiewicz
- University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland
| | - Barbara Lipinska
- University of Gdansk, Department of Biochemistry, Kładki 24, 80-822 Gdansk, Poland
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Characterization of DegQVh, a serine protease and a protective immunogen from a pathogenic Vibrio harveyi strain. Appl Environ Microbiol 2008; 74:6254-62. [PMID: 18723647 DOI: 10.1128/aem.00109-08] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio harveyi is an important marine pathogen that can infect a number of aquaculture species. V. harveyi degQ (degQ(Vh)), the gene encoding a DegQ homologue, was cloned from T4, a pathogenic V. harveyi strain isolated from diseased fish. DegQ(Vh) was closely related to the HtrA family members identified in other Vibrio species and could complement the temperature-sensitive phenotype of an Escherichia coli strain defective in degP. Expression of degQ(Vh) in T4 was modulated by temperature, possibly through the sigma(E)-like factor. Enzymatic analyses demonstrated that the recombinant DegQ(Vh) protein expressed in and purified from E. coli was an active serine protease whose activity required the integrity of the catalytic site and the PDZ domains. The optimal temperature and pH of the recombinant DegQ(Vh) protein were 50 degrees C and pH 8.0. A vaccination study indicated that the purified recombinant DegQ(Vh) was a protective immunogen that could confer protection upon fish against infection by V. harveyi. In order to improve the efficiency of DegQ(Vh) as a vaccine, a genetic construct in the form of the plasmid pAQ1 was built, in which the DNA encoding the processed DegQ(Vh) protein was fused with the DNA encoding the secretion region of AgaV, an extracellular beta-agarase. The E. coli strain harboring pAQ1 could express and secrete the chimeric DegQ(Vh) protein into the culture supernatant. Vaccination of fish with viable E. coli expressing chimeric degQ(Vh) significantly (P < 0.001) enhanced the survival of fish against V. harveyi challenge, which was possibly due to the relatively prolonged exposure of the immune system to the recombinant antigen produced constitutively, albeit at a gradually decreasing level, by the carrier strain.
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39
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Effect of folding factors in rescuing unstable heterologous lipase B to enhance its overexpression in the periplasm of Escherichia coli. Appl Microbiol Biotechnol 2008; 79:1035-44. [DOI: 10.1007/s00253-008-1514-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/16/2008] [Accepted: 04/19/2008] [Indexed: 11/26/2022]
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40
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Structural basis for the regulated protease and chaperone function of DegP. Nature 2008; 453:885-90. [PMID: 18496527 DOI: 10.1038/nature07004] [Citation(s) in RCA: 291] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 04/15/2008] [Indexed: 01/05/2023]
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41
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A conserved glycine residue of trimeric autotransporter domains plays a key role in Yersinia adhesin A autotransport. J Bacteriol 2007; 189:9011-9. [PMID: 17921300 DOI: 10.1128/jb.00985-07] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Yersinia adhesin A (YadA) is a trimeric autotransporter adhesin of enteric yersiniae. It consists of three major domains: a head mediating adherence to host cells, a stalk involved in serum resistance, and an anchor that forms a membrane pore and is responsible for the autotransport function. The anchor contains a glycine residue, nearly invariant throughout trimeric autotransporter adhesins, that faces the pore lumen. To address the role of this glycine, we replaced it with polar amino acids of increasing side chain size and expressed wild-type and mutant YadA in Escherichia coli. The mutations did not impair the YadA-mediated adhesion to collagen and to host cells or the host cell cytokine production, but they decreased the expression levels and stability of YadA trimers with increasing side chain size. Likewise, autoagglutination and resistance to serum were decreased in these mutants. We found that the periplasmic protease DegP is involved in the degradation of YadA and that in an E. coli degP deletion strain, mutant versions of YadA were expressed almost to wild-type levels. We conclude that the conserved glycine residue affects both the export and the stability of YadA and consequently some of its putative functions in pathogenesis.
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42
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Huesgen PF, Scholz P, Adamska I. The serine protease HhoA from Synechocystis sp. strain PCC 6803: substrate specificity and formation of a hexameric complex are regulated by the PDZ domain. J Bacteriol 2007; 189:6611-8. [PMID: 17616590 PMCID: PMC2045181 DOI: 10.1128/jb.00883-07] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enzymes of the ATP-independent Deg serine endopeptidase family are very flexible with regard to their substrate specificity. Some family members cleave only one substrate, while others act as general proteases on unfolded substrates. The proteolytic activity of Deg proteases is regulated by PDZ protein interaction domains. Here we characterized the HhoA protease from Synechocystis sp. strain PCC 6803 in vitro using several recombinant protein constructs. The proteolytic activity of HhoA was found to increase with temperature and basic pH and was stimulated by the addition of Mg(2+) or Ca(2+). We found that the single PDZ domain of HhoA played a critical role in regulating protease activity and in the assembly of a hexameric complex. Deletion of the PDZ domain strongly reduced proteolysis of a sterically challenging resorufin-labeled casein substrate, but unlabeled beta-casein was still degraded. Reconstitution of the purified HhoA with total membrane proteins isolated from Synechocystis sp. wild-type strain PCC 6803 and a DeltahhoA mutant resulted in specific degradation of selected proteins at elevated temperatures. We concluded that a single PDZ domain of HhoA plays a critical role in defining the protease activity and oligomerization state, combining the functions that are attributed to two PDZ domains in the homologous DegP protease from Escherichia coli. Based on this first enzymatic study of a Deg protease from cyanobacteria, we propose a general role for HhoA in the quality control of extracytoplasmic proteins, including membrane proteins, in Synechocystis sp. strain PCC 6803.
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Affiliation(s)
- Pitter F Huesgen
- Department of Physiology and Plant Biochemistry, University of Konstanz, Universitätsstrasse 10, D-78457 Konstanz, Germany
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43
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Skorko-Glonek J, Laskowska E, Sobiecka-Szkatula A, Lipinska B. Characterization of the chaperone-like activity of HtrA (DegP) protein from Escherichia coli under the conditions of heat shock. Arch Biochem Biophys 2007; 464:80-9. [PMID: 17485069 DOI: 10.1016/j.abb.2007.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Revised: 04/04/2007] [Accepted: 04/05/2007] [Indexed: 10/23/2022]
Abstract
The protective action of chaperone-like activity of HtrA protease against protein aggregation was studied. High levels of proteolytically inactive HtrAS210A (active center serine replaced by alanine) suppressed the temperature-sensitive phenotype of the htrA mutants. The ability of HtrAS210A to alleviate the lethality of htrA bacteria at high temperatures correlated well with the observed decrease of cellular level of large protein aggregates in cells overproducing HtrAS210A. The in vitro experiments proved that HtrA was very efficient in inhibiting the unfolded substrate (lysozyme) aggregation over a wide range of temperatures (30-45 degrees C). HtrA was able to bind to the denatured polypeptides and as a consequence limited their ability to form large aggregates. Our results suggest that HtrA may protect the bacterial cells from deleterious effects of heat shock not only by degrading the damaged proteins but by combination of the proteolytic and chaperoning activities.
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Affiliation(s)
- Joanna Skorko-Glonek
- University of Gdansk, Department of Biochemistry, Kladki 24, 80-822 Gdansk, Poland.
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44
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Wu MS, Pan KL, Chou CP. Effect of heat-shock proteins for relieving physiological stress and enhancing the production of penicillin acylase inEscherichia coli. Biotechnol Bioeng 2007; 96:956-66. [PMID: 16977620 DOI: 10.1002/bit.21161] [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: 11/11/2022]
Abstract
High-level expression of recombinant penicillin acylase (PAC) using the strong trc promoter system in Escherichia coli is frequently limited by the processing and folding of PAC precursors (proPAC) in the periplasm, resulting in physiological stress and inclusion body formation in this compartment. Periplasmic heat-shock proteins with protease or chaperone activity potentially offer a promise for overcoming this technical hurdle. In this study, the effect of the two genes encoding periplasmic heat-shock proteins, that is degP and fkpA, on pac overexpression was investigated and manipulation of the two genes to enhance the production of recombinant PAC was demonstrated. Both DeltadegP and DeltafkpA mutants showed defective culture performance primarily due to growth arrest. However, pac expression level was not seriously affected by the mutations, indicating that the two proteins were not directly involved in the pathway for periplasmic processing of proPAC. The growth defect caused by the two mutations (i.e., DeltadegP and DeltafkpA) was complemented by either one of the wild-type proteins, implying that the function of the two proteins could partially overlap in cells overexpressing pac. The possible role that the two heat-shock proteins played for suppression of physiological stress caused by pac overexpression is discussed.
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Affiliation(s)
- Ming-Shen Wu
- Department of Chemical Engineering, Feng Chia University, Taichung, Taiwan
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45
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Hasenbein S, Merdanovic M, Ehrmann M. Determinants of regulated proteolysis in signal transduction. Genes Dev 2007; 21:6-10. [PMID: 17210784 DOI: 10.1101/gad.1507807] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Sonja Hasenbein
- Zentrum für Medizinische Biotechnologie, Universität Duisburg-Essen, 45117 Essen, Germany
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46
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Charlson ES, Werner JN, Misra R. Differential effects of yfgL mutation on Escherichia coli outer membrane proteins and lipopolysaccharide. J Bacteriol 2006; 188:7186-94. [PMID: 17015657 PMCID: PMC1636225 DOI: 10.1128/jb.00571-06] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
YfgL together with NlpB, YfiO, and YaeT form a protein complex to facilitate the insertion of proteins into the outer membrane of Escherichia coli. Without YfgL, the levels of OmpA, OmpF, and LamB are significantly reduced, while OmpC levels are slightly reduced. In contrast, the level of TolC significantly increases in a yfgL mutant. When cells are depleted of YaeT or YfiO, levels of all outer membrane proteins examined, including OmpC and TolC, are severely reduced. Thus, while the assembly pathways of various nonlipoprotein outer membrane proteins may vary through the step involving YfgL, all assembly pathways in Escherichia coli converge at the step involving the YaeT/YfiO complex. The negative effect of yfgL mutation on outer membrane proteins may in part be due to elevated sigma E activity, which has been shown to downregulate the synthesis of various outer membrane proteins while upregulating the synthesis of periplasmic chaperones, foldases, and lipopolysaccharide. The data presented here suggest that the yfgL effect on outer membrane proteins also stems from a defective assembly apparatus, leading to aberrant outer membrane protein assembly, except for TolC, which assembles independent of YfgL. Consistent with this view, the simultaneous absence of YfgL and the major periplasmic protease DegP confers a synthetic lethal phenotype, presumably due to the toxic accumulation of unfolded outer membrane proteins. The results support the hypothesis that TolC and major outer membrane proteins compete for the YaeT/YfiO complex, since mutations that adversely affect synthesis or assembly of major outer membrane proteins lead to elevated TolC levels.
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Affiliation(s)
- Emily S Charlson
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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47
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Abstract
A novel mechanism of Escherichia coli porin regulation was discovered from multicopy suppressors that permitted growth of cells expressing a mutant OmpC protein in the absence of DegP. Analyses of two suppressors showed that both substantially lowered OmpC expression. Suppression activities were confined to a short DNA sequence, which we designated ipeX for inhibition of porin expression, and to DNA containing a 3'-truncated ompR gene. The major effect of ipeX on ompC expression was exerted posttranscriptionally, whereas the truncated OmpR protein reduced ompC transcription. ipeX was localized within an untranslated region of 247 base pairs between the stop codon of nmpC-a remnant porin gene from the cryptic phage qsr' (DLP12) genome-and its predicted Rho-independent transcriptional terminator. Interestingly, another prophage, PA-2, which encodes a porin similar to NmpC, known as Lc, has sequences downstream from lc identical to that of ipeX. PA-2 lysogenization leads to Lc expression and OmpC inhibition. Our data show that the synthesis of the lc transcript, whose 3' end contains the corresponding ipeX sequence, inhibits OmpC expression. Overexpression of ipeX RNA inhibited both OmpC and OmpF expression but not that of OmpA. ompC-phoA chimeric gene constructs revealed a 248-bp untranslated region of ompC required for ipeX-mediated inhibition. However, no sequence complementarity was found between ipeX and this region of ompC, indicating that inhibition may not involve simple base pairing between the two RNA molecules. The effect of ipeX on ompC, but not on ompF, was independent of the RNA chaperone Hfq.
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Affiliation(s)
- Maria Castillo-Keller
- Faculty of Cellular and Molecular Sciences, School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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48
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Abstract
The outer membrane is the first line of contact between Gram-negative bacteria and their external environment. Embedded in the outer membrane are integral outer membrane proteins (OMPs) that perform a diverse range of tasks. OMPs are synthesized in the cytoplasm and are translocated across the inner membrane and probably diffuse through the periplasm before they are inserted into the outer membrane in a folded and biologically active form. Passage through the periplasm presents a number of challenges, due to the hydrophobic nature of the OMPs and the choice of membranes into which they can insert. Recently, a number of periplasmic proteins and one OMP have been shown to play a role in OMP biogenesis. In this review, we describe what is known about these folding factors and how they function in a biological context. In particular, we focus on how they interact with the OMPs at the molecular level and present a comprehensive overview of data relating to a possible effect on OMP folding yield and kinetics. Furthermore, we discuss the role of lipo-chaperones, i.e. lipopolysaccharide and phospholipids, in OMP folding. Important advances have clearly been made in the field, but much work remains to be done, particularly in terms of describing the biophysical basis for the chaperone-OMP interactions which so intricately regulate OMP biogenesis.
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Affiliation(s)
- Jesper E Mogensen
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
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49
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Bishop RE. The lipid A palmitoyltransferase PagP: molecular mechanisms and role in bacterial pathogenesis. Mol Microbiol 2005; 57:900-12. [PMID: 16091033 DOI: 10.1111/j.1365-2958.2005.04711.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Palmitoylated lipid A can both protect pathogenic bacteria from host immune defences and attenuate the activation of those same defences through the TLR4 signal transduction pathway. A palmitate chain from a phospholipid is incorporated into lipid A by an outer membrane enzyme PagP, which is an 8-stranded antiparallel beta-barrel preceded by an amino-terminal amphipathic alpha-helix. The PagP barrel axis is tilted by 25 degrees with respect to the membrane normal. An interior hydrophobic pocket in the outer leaflet-exposed half of the molecule functions as a hydrocarbon ruler that allows the enzyme to distinguish palmitate from other acyl chains found in phospholipids. Internalization of a phospholipid palmitoyl group within the barrel appears to occur by lateral diffusion from the outer leaflet through non-hydrogen-bonded regions between beta-strands. The MsbA-dependent trafficking of lipids from the inner membrane to the outer membrane outer leaflet is necessary for lipid A palmitoylation in vivo. The mechanisms by which bacteria regulate pagP gene expression strikingly reflect the corresponding pathogenic lifestyle of the bacterium. Variations on PagP structure and function can be illustrated with the known homologues from Gram-negative bacteria, which include pathogens of humans and other mammals in addition to pathogens of insects and plants. The PagP enzyme is potentially a target for the development of anti-infective agents, a probe of outer membrane lipid asymmetry, and a tool for the synthesis of lipid A-based vaccine adjuvants and endotoxin antagonists.
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Affiliation(s)
- Russell E Bishop
- Departments of Laboratory Medicine and Pathobiology, and Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
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Groll M, Bochtler M, Brandstetter H, Clausen T, Huber R. Molecular machines for protein degradation. Chembiochem 2005; 6:222-56. [PMID: 15678420 DOI: 10.1002/cbic.200400313] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
One of the most precisely regulated processes in living cells is intracellular protein degradation. The main component of the degradation machinery is the 20S proteasome present in both eukaryotes and prokaryotes. In addition, there exist other proteasome-related protein-degradation machineries, like HslVU in eubacteria. Peptides generated by proteasomes and related systems can be used by the cell, for example, for antigen presentation. However, most of the peptides must be degraded to single amino acids, which are further used in cell metabolism and for the synthesis of new proteins. Tricorn protease and its interacting factors are working downstream of the proteasome and process the peptides into amino acids. Here, we summarise the current state of knowledge about protein-degradation systems, focusing in particular on the proteasome, HslVU, Tricorn protease and its interacting factors and DegP. The structural information about these protein complexes opens new possibilities for identifying, characterising and elucidating the mode of action of natural and synthetic inhibitors, which affects their function. Some of these compounds may find therapeutic applications in contemporary medicine.
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Affiliation(s)
- Michael Groll
- Adolf-Butenandt-Institut Physiological Chemistry, LMU München, Butenandtstrasse 5, Gebäude B, 81377 München, Germany.
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