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Mortier J, Cambré A, Schack S, Christie G, Aertsen A. Impact of Protein Aggregates on Sporulation and Germination of Bacillus subtilis. Microorganisms 2023; 11:2365. [PMID: 37764209 PMCID: PMC10536567 DOI: 10.3390/microorganisms11092365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
In order to improve our general understanding of protein aggregate (PA) management and impact in bacteria, different model systems and processes need to be investigated. As such, we developed an inducible synthetic PA model system to investigate PA dynamics in the Gram-positive model organism Bacillus subtilis. This confirmed previous observations that PA segregation in this organism seems to follow the Escherichia coli paradigm of nucleoid occlusion governing polar localization and asymmetric segregation during vegetative growth. However, our findings also revealed that PAs can readily persist throughout the entire sporulation process after encapsulation in the forespore during sporulation. Moreover, no deleterious effects of PA presence on sporulation, germination and spore survival against heat or UV stress could be observed. Our findings therefore indicate that the sporulation process is remarkably robust against perturbations by PAs and misfolded proteins.
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Affiliation(s)
- Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
| | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
| | - Sina Schack
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK; (S.S.); (G.C.)
| | - Graham Christie
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK; (S.S.); (G.C.)
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, B-3000 Leuven, Belgium; (J.M.); (A.C.)
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2
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Matavacas J, von Wachenfeldt C. Update on the Protein Homeostasis Network in Bacillus subtilis. Front Microbiol 2022; 13:865141. [PMID: 35350626 PMCID: PMC8957991 DOI: 10.3389/fmicb.2022.865141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 02/15/2022] [Indexed: 11/13/2022] Open
Abstract
Protein homeostasis is fundamental to cell function and survival. It relies on an interconnected network of processes involving protein synthesis, folding, post-translational modification and degradation as well as regulators of these processes. Here we provide an update on the roles, regulation and subcellular localization of the protein homeostasis machinery in the Gram-positive model organism Bacillus subtilis. We discuss emerging ideas and current research gaps in the field that, if tackled, increase our understanding of how Gram-positive bacteria, including several human pathogens, maintain protein homeostasis and cope with stressful conditions that challenge their survival.
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The Division Defect of a Bacillus subtilis minD noc Double Mutant Can Be Suppressed by Spx-Dependent and Spx-Independent Mechanisms. J Bacteriol 2021; 203:e0024921. [PMID: 34181483 DOI: 10.1128/jb.00249-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
During growth, bacteria increase in size and divide. Division is initiated by the formation of the Z-ring, a ring-like cytoskeletal structure formed by treadmilling protofilaments of the tubulin homolog FtsZ. FtsZ localization is thought to be controlled by the Min and Noc systems, and here we explore why cell division fails at high temperature when the Min and Noc systems are simultaneously mutated. Microfluidic analysis of a minD noc double mutant indicated that FtsZ formed proto-Z-rings at periodic interchromosome locations but that the rings failed to mature and become functional. Extragenic suppressor analysis indicated that a variety of mutations restored high temperature growth to the minD noc double mutant, and while many were likely pleiotropic, others implicated the proteolysis of the transcription factor Spx. Further analysis indicated that a Spx-dependent pathway activated the expression of ZapA, a protein that primarily compensates for the absence of Noc. In addition, an Spx-independent pathway reduced the length of the cytokinetic period, perhaps by increasing divisome activity. Finally, we provide evidence of an as-yet-unidentified protein that is activated by Spx and governs the frequency of polar division and minicell formation. IMPORTANCE Bacteria must properly position the location of the cell division machinery in order to grow, divide, and ensure each daughter cell receives one copy of the chromosome. In Bacillus subtilis, cell division site selection depends on the Min and Noc systems, and while neither is individually essential, cells fail to grow at high temperature when both are mutated. Here, we show that cell division fails in the absence of Min and Noc, due not to a defect in FtsZ localization but rather to a failure in the maturation of the cell division machinery. Suppressor mutations that restored growth were selected, and while some activated the expression of ZapA via the Spx stress response pathway, others appeared to directly enhance divisome activity.
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CwlQ Is Required for Swarming Motility but Not Flagellar Assembly in Bacillus subtilis. J Bacteriol 2021; 203:JB.00029-21. [PMID: 33649146 DOI: 10.1128/jb.00029-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/22/2021] [Indexed: 11/20/2022] Open
Abstract
Lytic enzymes play an essential role in the remodeling of bacterial peptidoglycan (PG), an extracellular mesh-like structure that retains the membrane in the context of high internal osmotic pressure. Peptidoglycan must be unfailingly stable to preserve cell integrity, but must also be dynamically remodeled for the cell to grow, divide, and insert macromolecular machines. The flagellum is one such macromolecular machine that transits the PG, and flagellar insertion is aided by localized activity of a dedicated PG lyase in Gram-negative bacteria. To date, there is no known dedicated lyase in Gram-positive bacteria for the insertion of flagella. Here, we take a reverse-genetic candidate-gene approach and find that cells mutated for the lytic transglycosylase CwlQ exhibit a severe defect in flagellum-dependent swarming motility. We further show that CwlQ is expressed by the motility sigma factor SigD and is secreted by the type III secretion system housed inside the flagellum. Nonetheless, cells with mutations of CwlQ remain proficient for flagellar biosynthesis even when mutated in combination with four other lyases related to motility (LytC, LytD, LytF, and CwlO). The PG lyase (or lyases) essential for flagellar synthesis in B. subtilis, if any, remains unknown.IMPORTANCE Bacteria are surrounded by a wall of peptidoglycan and early work in Bacillus subtilis was the first to suggest that bacteria needed to enzymatically remodel the wall to permit insertion of the flagellum. No PG remodeling enzyme alone or in combination, however, has been found to be essential for flagellar assembly in B. subtilis Here, we take a reverse-genetic candidate-gene approach and find that the PG lytic transglycosylase CwlQ is required for swarming motility. Subsequent characterization determined that while CwlQ was coexpressed with motility genes and is secreted by the flagellar secretion apparatus, it was not required for flagellar synthesis. The PG lyase needed for flagellar assembly in B. subtilis remains unknown.
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5
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ClpC-Mediated Sporulation Regulation at Engulfment Stage in Bacillus anthracis. Indian J Microbiol 2021; 61:170-179. [PMID: 33927458 DOI: 10.1007/s12088-021-00927-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/23/2021] [Indexed: 12/24/2022] Open
Abstract
Bacterial sporulation is a conserved process utilized by members of Bacillus genus and Clostridium in response to stress such as nutrient or temperature. Sporulation initiation is triggered by stress signals perceived by bacterial cell that leads to shutdown of metabolic pathways of bacterial cells. The mechanism of sporulation involves a complex network that is regulated at various checkpoints to form the viable bacterial spore. Engulfment is one such check point that drives the required cellular rearrangement necessary for the spore assembly and is mediated by bacterial proteolytic machinery that involves association of various Clp ATPases and ClpP protease. The present study highlights the importance of degradation of an anti-sigma factor F, SpoIIAB by ClpCP proteolytic machinery playing a crucial role in culmination of engulfment process during the sporulation in Bacillus anthracis.
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Tn FLX: a Third-Generation mariner-Based Transposon System for Bacillus subtilis. Appl Environ Microbiol 2020; 86:AEM.02893-19. [PMID: 32169936 DOI: 10.1128/aem.02893-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/26/2020] [Indexed: 01/05/2023] Open
Abstract
Random transposon mutagenesis is a powerful and unbiased genetic approach to answer fundamental biological questions. Here, we introduce an improved mariner-based transposon system with enhanced stability during propagation and versatile applications in mutagenesis. We used a low-copy-number plasmid as a transposon delivery vehicle, which affords a lower frequency of unintended recombination during vector construction and propagation in Escherichia coli We generated a variety of transposons allowing for gene disruption or artificial overexpression, each in combination with one of four different antibiotic resistance markers. In addition, we provide transposons that will report gene/protein expression due to transcriptional or translational coupling. We believe that the TnFLX system will help enhance the flexibility of future transposon modification and application in Bacillus and other organisms.IMPORTANCE The stability of transposase-encoding vectors during cloning and propagation is crucial for the reliable application of transposons. Here, we increased the stability of the mariner delivery vehicle in E. coli Moreover, the TnFLX transposon system will improve the application of forward genetic methods with an increased number of antibiotic resistance markers and the ability to generate unbiased green fluorescent protein (GFP) fusions to report on protein translation and subcellular localization.
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Staphylococcus aureus ClpX localizes at the division septum and impacts transcription of genes involved in cell division, T7-secretion, and SaPI5-excision. Sci Rep 2019; 9:16456. [PMID: 31712583 PMCID: PMC6848492 DOI: 10.1038/s41598-019-52823-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 10/12/2019] [Indexed: 11/25/2022] Open
Abstract
In all living cells, molecular chaperones are essential for facilitating folding and unfolding of proteins. ClpX is a highly conserved ATP-dependent chaperone that besides functioning as a classical chaperone can associate with ClpP to form the ClpXP protease. To investigate the relative impact of the ClpXP protease and the ClpX chaperone in cell physiology of the important pathogenic bacterium Staphylococcus aureus, we assessed the transcriptional changes induced by inactivating only ClpXP, or by completely deleting ClpX. This analysis revealed that ClpX has a profound impact on S. aureus cell physiology that is mediated primarily via ClpXP-dependent pathways. As an example, ClpX impacts expression of virulence genes entirely via ClpXP-dependent mechanisms. Furthermore, ClpX controls a high number of genes and sRNAs via pathways involving both ClpXP protease and ClpX chaperone activities; an interesting example being genes promoting excision and replication of the pathogenicity island SaPI5. Independently of ClpP, ClpX, impacts transcription of only a restricted number of genes involved in peptidoglycan synthesis, cell division, and type seven secretion. Finally, we demonstrate that ClpX localizes in single foci in close proximity to the division septum lending support to the idea that ClpX plays a role in S. aureus cell division.
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8
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Roles for ClpXP in regulating the circadian clock in Synechococcus elongatus. Proc Natl Acad Sci U S A 2018; 115:E7805-E7813. [PMID: 30061418 DOI: 10.1073/pnas.1800828115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In cyanobacteria, the KaiABC posttranslational oscillator drives circadian rhythms of gene expression and controls the timing of cell division. The Kai-based oscillator can be reconstituted in vitro, demonstrating that the clock can run without protein synthesis and degradation; however, protein degradation is known to be important for clock function in vivo. Here, we report that strains deficient in the ClpXP1P2 protease have, in addition to known long-period circadian rhythms, an exaggerated ability to synchronize with the external environment (reduced "jetlag") compared with WT strains. Deletion of the ClpX chaperone, but not the protease subunits ClpP1 or ClpP2, results in cell division defects in a manner that is dependent on the expression of a dusk-peaking factor. We propose that chaperone activities of ClpX are required to coordinate clock control of cell division whereas the protease activities of the ClpXP1P2 complex are required to maintain appropriate periodicity of the clock and its synchronization with the external environment.
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9
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Signal Peptidase Is Necessary and Sufficient for Site 1 Cleavage of RsiV in Bacillus subtilis in Response to Lysozyme. J Bacteriol 2018; 200:JB.00663-17. [PMID: 29358498 DOI: 10.1128/jb.00663-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/18/2018] [Indexed: 01/09/2023] Open
Abstract
Extracytoplasmic function (ECF) σ factors are a diverse family of alternative σ factors that allow bacteria to sense and respond to changes in the environment. σV is an ECF σ factor found primarily in low-GC Gram-positive bacteria and is required for lysozyme resistance in several opportunistic pathogens. In the absence of lysozyme, σV is inhibited by the anti-σ factor RsiV. In response to lysozyme, RsiV is degraded via the process of regulated intramembrane proteolysis (RIP). RIP is initiated by cleavage of RsiV at site 1, which allows the intramembrane protease RasP to cleave RsiV within the transmembrane domain at site 2 and leads to activation of σV Previous work suggested that RsiV is cleaved by signal peptidase at site 1. Here we demonstrate in vitro that signal peptidase is sufficient for cleavage of RsiV only in the presence of lysozyme and provide evidence that multiple Bacillus subtilis signal peptidases can cleave RsiV in vitro This cleavage is dependent upon the concentration of lysozyme, consistent with previous work that showed that binding to RsiV was required for σV activation. We also show that signal peptidase activity is required for site 1 cleavage of RsiV in vivo Thus, we demonstrate that signal peptidase is the site 1 protease for RsiV.IMPORTANCE Extracytoplasmic function (ECF) σ factors are a diverse family of alternative σ factors that respond to extracellular signals. The ECF σ factor σV is present in many low-GC Gram-positive bacteria and induces resistance to lysozyme, a component of the innate immune system. The anti-σ factor RsiV inhibits σV activity in the absence of lysozyme. Lysozyme binds RsiV, which initiates a proteolytic cascade leading to destruction of RsiV and activation of σV This proteolytic cascade is initiated by signal peptidase, a component of the general secretory system. We show that signal peptidase is necessary and sufficient for cleavage of RsiV at site 1 in the presence of lysozyme. This report describes a role for signal peptidase in controlling gene expression.
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10
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Yu Y, Yan F, He Y, Qin Y, Chen Y, Chai Y, Guo JH. The ClpY-ClpQ protease regulates multicellular development in Bacillus subtilis. Microbiology (Reading) 2018; 164:848-862. [DOI: 10.1099/mic.0.000658] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Yiyang Yu
- Department of Plant Pathology, Nanjing Agricultural University; Engineering Center of Bioresource Pesticide in Jiangsu Province; Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing 210095, PR China
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Fang Yan
- Department of Plant Pathology, Nanjing Agricultural University; Engineering Center of Bioresource Pesticide in Jiangsu Province; Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing 210095, PR China
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Yinghao He
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Yuxuan Qin
- Department of Biology, Northeastern University, Boston, MA 02115, USA
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Yun Chen
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, PR China
| | - Yunrong Chai
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Jian-hua Guo
- Department of Plant Pathology, Nanjing Agricultural University; Engineering Center of Bioresource Pesticide in Jiangsu Province; Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing 210095, PR China
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11
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Riley EP, Trinquier A, Reilly ML, Durchon M, Perera VR, Pogliano K, Lopez-Garrido J. Spatiotemporally regulated proteolysis to dissect the role of vegetative proteins during Bacillus subtilis sporulation: cell-specific requirement of σ H and σ A. Mol Microbiol 2018; 108:45-62. [PMID: 29363854 DOI: 10.1111/mmi.13916] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/19/2018] [Accepted: 01/21/2018] [Indexed: 11/27/2022]
Abstract
Sporulation in Bacillus subtilis is a paradigm of bacterial development, which involves the interaction between a larger mother cell and a smaller forespore. The mother cell and the forespore activate different genetic programs, leading to the production of sporulation-specific proteins. A critical gap in our understanding of sporulation is how vegetative proteins, made before sporulation initiation, contribute to spore formation. Here we present a system, spatiotemporally regulated proteolysis (STRP), which enables the rapid, developmentally regulated degradation of target proteins, thereby providing a suitable method to dissect the cell- and developmental stage-specific role of vegetative proteins. STRP has been used to dissect the role of two major vegetative sigma factors, σH and σA , during sporulation. The results suggest that σH is only required in predivisional cells, where it is essential for sporulation initiation, but that it is dispensable during subsequent steps of spore formation. However, evidence has been provided that σA plays different roles in the mother cell, where it replenishes housekeeping functions, and in the forespore, where it plays an unexpected role in promoting spore germination and outgrowth. Altogether, the results demonstrate that STRP has the potential to provide a comprehensive molecular dissection of every stage of sporulation, germination and outgrowth.
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Affiliation(s)
- Eammon P Riley
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Aude Trinquier
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Madeline L Reilly
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Marine Durchon
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Varahenage R Perera
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Kit Pogliano
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Javier Lopez-Garrido
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
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12
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Elsholz AKW, Birk MS, Charpentier E, Turgay K. Functional Diversity of AAA+ Protease Complexes in Bacillus subtilis. Front Mol Biosci 2017; 4:44. [PMID: 28748186 PMCID: PMC5506225 DOI: 10.3389/fmolb.2017.00044] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 06/15/2017] [Indexed: 12/20/2022] Open
Abstract
Here, we review the diverse roles and functions of AAA+ protease complexes in protein homeostasis, control of stress response and cellular development pathways by regulatory and general proteolysis in the Gram-positive model organism Bacillus subtilis. We discuss in detail the intricate involvement of AAA+ protein complexes in controlling sporulation, the heat shock response and the role of adaptor proteins in these processes. The investigation of these protein complexes and their adaptor proteins has revealed their relevance for Gram-positive pathogens and their potential as targets for new antibiotics.
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Affiliation(s)
- Alexander K W Elsholz
- Department of Regulation in Infection Biology, Max Planck Institute for Infection BiologyBerlin, Germany
| | - Marlene S Birk
- Department of Regulation in Infection Biology, Max Planck Institute for Infection BiologyBerlin, Germany
| | - Emmanuelle Charpentier
- Department of Regulation in Infection Biology, Max Planck Institute for Infection BiologyBerlin, Germany.,The Laboratory for Molecular Infection Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå UniversityUmeå, Sweden.,Humboldt UniversityBerlin, Germany
| | - Kürşad Turgay
- Faculty of Natural Sciences, Institute of Microbiology, Leibniz UniversitätHannover, Germany
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13
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Analysis of a dual domain phosphoglycosyl transferase reveals a ping-pong mechanism with a covalent enzyme intermediate. Proc Natl Acad Sci U S A 2017. [PMID: 28630348 DOI: 10.1073/pnas.1703397114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Phosphoglycosyl transferases (PGTs) are integral membrane proteins with diverse architectures that catalyze the formation of polyprenol diphosphate-linked glycans via phosphosugar transfer from a nucleotide diphosphate-sugar to a polyprenol phosphate. There are two PGT superfamilies that differ significantly in overall structure and topology. The polytopic PGT superfamily, represented by MraY and WecA, has been the subject of many studies because of its roles in peptidoglycan and O-antigen biosynthesis. In contrast, less is known about a second, extensive superfamily of PGTs that reveals a core structure with dual domain architecture featuring a C-terminal soluble globular domain and a predicted N-terminal membrane-associated domain. Representative members of this superfamily are the Campylobacter PglCs, which initiate N-linked glycoprotein biosynthesis and are implicated in virulence and pathogenicity. Despite the prevalence of dual domain PGTs, their mechanism of action is unknown. Here, we present the mechanistic analysis of PglC, a prototypic dual domain PGT from Campylobacter concisus Using a luminescence-based assay, together with substrate labeling and kinetics-based approaches, complementary experiments were carried out that support a ping-pong mechanism involving a covalent phosphosugar intermediate for PglC. Significantly, mass spectrometry-based approaches identified Asp93, which is part of a highly conserved AspGlu dyad found in all dual domain PGTs, as the active-site nucleophile of the enzyme involved in the formation of the covalent adduct. The existence of a covalent phosphosugar intermediate provides strong support for a ping-pong mechanism of PglC, differing fundamentally from the ternary complex mechanisms of representative polytopic PGTs.
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14
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LaBreck CJ, May S, Viola MG, Conti J, Camberg JL. The Protein Chaperone ClpX Targets Native and Non-native Aggregated Substrates for Remodeling, Disassembly, and Degradation with ClpP. Front Mol Biosci 2017; 4:26. [PMID: 28523271 PMCID: PMC5415555 DOI: 10.3389/fmolb.2017.00026] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 04/07/2017] [Indexed: 01/21/2023] Open
Abstract
ClpX is a member of the Clp/Hsp100 family of ATP-dependent chaperones and partners with ClpP, a compartmentalized protease, to degrade protein substrates bearing specific recognition signals. ClpX targets specific proteins for degradation directly or with substrate-specific adaptor proteins. Native substrates of ClpXP include proteins that form large oligomeric assemblies, such as MuA, FtsZ, and Dps in Escherichia coli. To remodel large oligomeric substrates, ClpX utilizes multivalent targeting strategies and discriminates between assembled and unassembled substrate conformations. Although ClpX and ClpP are known to associate with protein aggregates in E. coli, a potential role for ClpXP in disaggregation remains poorly characterized. Here, we discuss strategies utilized by ClpX to recognize native and non-native protein aggregates and the mechanisms by which ClpX alone, and with ClpP, remodels the conformations of various aggregates. We show that ClpX promotes the disassembly and reactivation of aggregated Gfp-ssrA through specific substrate remodeling. In the presence of ClpP, ClpX promotes disassembly and degradation of aggregated substrates bearing specific ClpX recognition signals, including heat-aggregated Gfp-ssrA, as well as polymeric and heat-aggregated FtsZ, which is a native ClpXP substrate in E. coli. Finally, we show that ClpX is present in insoluble aggregates and prevents the accumulation of thermal FtsZ aggregates in vivo, suggesting that ClpXP participates in the management of aggregates bearing ClpX recognition signals.
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Affiliation(s)
- Christopher J LaBreck
- Department of Cell and Molecular Biology, University of Rhode IslandKingston, RI, USA
| | - Shannon May
- Department of Cell and Molecular Biology, University of Rhode IslandKingston, RI, USA
| | - Marissa G Viola
- Department of Cell and Molecular Biology, University of Rhode IslandKingston, RI, USA
| | - Joseph Conti
- Department of Cell and Molecular Biology, University of Rhode IslandKingston, RI, USA
| | - Jodi L Camberg
- Department of Cell and Molecular Biology, University of Rhode IslandKingston, RI, USA
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15
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Abstract
Determining the mechanisms of enzymatic regulation is central to the study of cellular metabolism. Regulation of enzyme activity via polymerization-mediated strategies has been shown to be widespread, and plays a vital role in mediating cellular homeostasis. In this review, we begin with an overview of the filamentation of CTP synthase, which forms filamentous structures termed cytoophidia. We then highlight other important examples of the phenomenon. Moreover, we discuss recent data relating to the regulation of enzyme activity by compartmentalization into cytoophidia. Finally, we hypothesize potential roles for enzyme filament formation in the regulation of metabolism, development and disease.
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Affiliation(s)
- Gabriel N Aughey
- a MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics , University of Oxford , Oxford , UK
| | - Ji-Long Liu
- a MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics , University of Oxford , Oxford , UK
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16
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Predation by Myxococcus xanthus induces Bacillus subtilis to form spore-filled megastructures. Appl Environ Microbiol 2014; 81:203-10. [PMID: 25326308 DOI: 10.1128/aem.02448-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biofilm formation is a common mechanism for surviving environmental stress and can be triggered by both intraspecies and interspecies interactions. Prolonged predator-prey interactions between the soil bacterium Myxococcus xanthus and Bacillus subtilis were found to induce the formation of a new type of B. subtilis biofilm, termed megastructures. Megastructures are tree-like brachiations that are as large as 500 μm in diameter, are raised above the surface between 150 and 200 μm, and are filled with viable endospores embedded within a dense matrix. Megastructure formation did not depend on TasA, EpsE, SinI, RemA, or surfactin production and thus is genetically distinguishable from colony biofilm formation on MSgg medium. As B. subtilis endospores are not susceptible to predation by M. xanthus, megastructures appear to provide an alternative mechanism for survival. In addition, M. xanthus fruiting bodies were found immediately adjacent to the megastructures in nearly all instances, suggesting that M. xanthus is unable to acquire sufficient nutrients from cells housed within the megastructures. Lastly, a B. subtilis mutant lacking the ability to defend itself via bacillaene production formed megastructures more rapidly than the parent. Together, the results indicate that production of the megastructure facilitates B. subtilis escape into dormancy via sporulation.
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17
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Das A, Das A. Delineation of polar localization domains of Agrobacterium tumefaciens type IV secretion apparatus proteins VirB4 and VirB11. Microbiologyopen 2014; 3:793-802. [PMID: 25220247 PMCID: PMC4234268 DOI: 10.1002/mbo3.208] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/12/2014] [Accepted: 07/22/2014] [Indexed: 11/16/2022] Open
Abstract
Agrobacterium tumefaciens transfers DNA and proteins to a plant cell through a type IV secretion apparatus assembled by the VirB proteins. All VirB proteins localized to a cell pole, although these conclusions are in dispute. To study subcellular location of the VirB proteins and to identify determinants of their subcellular location, we tagged two proteins, VirB4 and VirB11, with the visual marker green fluorescent protein (GFP) and studied localization of the fusion proteins by epifluorescence microscopy. Both GFP-VirB4 and GFP-VirB11 fusions localized to a single cell pole. GFP-VirB11 was also functional in DNA transfer. To identify the polar localization domains (PLDs) of VirB4 and VirB11, we analyzed fusions of GFP with smaller segments of the two proteins. Two noncontiguous regions in VirB4, residues 236–470 and 592–789, contain PLDs. The VirB11 PLD mapped to a 69 amino acid segment, residues 149–217, in the central region of the protein. These domains are probably involved in interactions that target the two proteins to a cell pole.
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Affiliation(s)
- Aditi Das
- Roseville Area High School, Roseville, Minnesota, 55113
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18
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Williams B, Bhat N, Chien P, Shapiro L. ClpXP and ClpAP proteolytic activity on divisome substrates is differentially regulated following the Caulobacter asymmetric cell division. Mol Microbiol 2014; 93:853-66. [PMID: 24989075 PMCID: PMC4285227 DOI: 10.1111/mmi.12698] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2014] [Indexed: 12/01/2022]
Abstract
Proteolytic control of Caulobacter cell cycle proteins is primarily executed by ClpXP, a dynamically localized protease implicated in turnover of several factors critical for faithful cell cycle progression. Here, we show that the transient midcell localization of ClpXP that precedes cytokinesis requires the FtsZ component of the divisome. Although ClpAP does not exhibit subcellular localization, FtsZ is a substrate of both ClpXP and ClpAP in vivo and in vitro. A peptide containing the C-terminal portion of the FtsA divisome protein is a substrate of both ClpXP and ClpAP in vitro but is primarily degraded by ClpAP in vivo. Caulobacter carries out an asymmetric division in which FtsZ and FtsA are stable in stalked cells but degraded in the non-replicative swarmer cell where ClpAP alone degrades FtsA and both ClpAP and ClpXP degrade FtsZ. While asymmetric division in Caulobacter normally yields larger stalked and smaller swarmer daughters, we observe a loss of asymmetric size distribution among daughter cells when clpA is depleted from a strain in which FtsZ is constitutively produced. Taken together, these results suggest that the activity of both ClpXP and ClpAP on divisome substrates is differentially regulated in daughter cells.
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Affiliation(s)
- Brandon Williams
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA
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19
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Singh LK, Dhasmana N, Sajid A, Kumar P, Bhaduri A, Bharadwaj M, Gandotra S, Kalia VC, Das TK, Goel AK, Pomerantsev AP, Misra R, Gerth U, Leppla SH, Singh Y. clpC operon regulates cell architecture and sporulation in Bacillus anthracis. Environ Microbiol 2014; 17:855-65. [PMID: 24947607 DOI: 10.1111/1462-2920.12548] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
The clpC operon is known to regulate several processes such as genetic competence, protein degradation and stress survival in bacteria. Here, we describe the role of clpC operon in Bacillus anthracis. We generated knockout strains of the clpC operon genes to investigate the impact of CtsR, McsA, McsB and ClpC deletion on essential processes of B. anthracis. We observed that growth, cell division, sporulation and germination were severely affected in mcsB and clpC deleted strains, while none of deletions affected toxin secretion. Growth defect in these strains was pronounced at elevated temperature. The growth pattern gets restored on complementation of mcsB and clpC in respective mutants. Electron microscopic examination revealed that mcsB and clpC deletion also causes defect in septum formation leading to cell elongation. These vegetative cell deformities were accompanied by inability of mutant strains to generate morphologically intact spores. Higher levels of polyhydroxybutyrate granules accumulation were also observed in these deletion strains, indicating a defect in sporulation process. Our results demonstrate, for the first time, the vital role played by McsB and ClpC in physiology of B. anthracis and open up further interest on this operon, which might be of importance to success of B. anthracis as pathogen.
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Affiliation(s)
- Lalit K Singh
- CSIR-Institute of Genomics and Integrative Biology, Delhi, 110007, India
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20
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Streptococcus pyogenes polymyxin B-resistant mutants display enhanced ExPortal integrity. J Bacteriol 2014; 196:2563-77. [PMID: 24794568 DOI: 10.1128/jb.01596-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The ExPortal protein secretion organelle in Streptococcus pyogenes is an anionic phospholipid-containing membrane microdomain enriched in Sec translocons and postsecretion protein biogenesis factors. Polymyxin B binds to and disrupts ExPortal integrity, resulting in defective secretion of several toxins. To gain insight into factors that influence ExPortal organization, a genetic screen was conducted to select for spontaneous polymyxin B-resistant mutants displaying enhanced ExPortal integrity. Whole-genome resequencing of 25 resistant mutants revealed from one to four mutations per mutant genome clustered primarily within a core set of 10 gene groups. Construction of mutants with individual deletions or insertions demonstrated that 7 core genes confer resistance and enhanced ExPortal integrity through loss of function, while 3 were likely due to gain of function and/or combinatorial effects. Core resistance genes include a transcriptional regulator of lipid biosynthesis, several genes involved in nutrient acquisition, and a variety of genes involved in stress responses. Two members of the latter class also function as novel regulators of the secreted SpeB cysteine protease. Analysis of the most frequently isolated mutation, a single nucleotide deletion in a track of 9 consecutive adenine residues in pstS, encoding a component of a high-affinity Pi transporter, suggests that this sequence functions as a molecular switch to facilitate stress adaptation. Together, these data suggest the existence of a membrane stress response that promotes enhanced ExPortal integrity and resistance to cationic antimicrobial peptides.
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Konovalova A, Søgaard-Andersen L, Kroos L. Regulated proteolysis in bacterial development. FEMS Microbiol Rev 2013; 38:493-522. [PMID: 24354618 DOI: 10.1111/1574-6976.12050] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/03/2013] [Accepted: 10/14/2013] [Indexed: 11/30/2022] Open
Abstract
Bacteria use proteases to control three types of events temporally and spatially during the processes of morphological development. These events are the destruction of regulatory proteins, activation of regulatory proteins, and production of signals. While some of these events are entirely cytoplasmic, others involve intramembrane proteolysis of a substrate, transmembrane signaling, or secretion. In some cases, multiple proteolytic events are organized into pathways, for example turnover of a regulatory protein activates a protease that generates a signal. We review well-studied and emerging examples and identify recurring themes and important questions for future research. We focus primarily on paradigms learned from studies of model organisms, but we note connections to regulated proteolytic events that govern bacterial adaptation, biofilm formation and disassembly, and pathogenesis.
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Affiliation(s)
- Anna Konovalova
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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22
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Abstract
The soil-dwelling bacterium Bacillus subtilis is widely used as a model organism to study the Gram-positive branch of Bacteria. A variety of different developmental pathways, such as endospore formation, genetic competence, motility, swarming and biofilm formation, have been studied in this organism. These processes are intricately connected and regulated by networks containing e.g. alternative sigma factors, two-component systems and other regulators. Importantly, in some of these regulatory networks the activity of important regulatory factors is controlled by proteases. Furthermore, together with chaperones, the same proteases constitute the cellular protein quality control (PQC) network, which plays a crucial role in protein homeostasis and stress tolerance of this organism. In this review, we will present the current knowledge on regulatory and general proteolysis in B. subtilis and discuss its involvement in developmental pathways and cellular stress management.
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Affiliation(s)
- Noël Molière
- Institut für Mikrobiologie, Leibniz Universität Hannover, Schneiderberg 50, 30167, Hannover, Germany,
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23
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Segregation of molecules at cell division reveals native protein localization. Nat Methods 2012; 9:480-2. [PMID: 22484850 PMCID: PMC3779060 DOI: 10.1038/nmeth.1955] [Citation(s) in RCA: 264] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 03/09/2012] [Indexed: 12/11/2022]
Abstract
We introduce a non-intrusive method exploiting post-division single-cell variability to validate protein localization. The results show that Clp proteases, widely reported to form biologically relevant foci, are in fact uniformly distributed inside Escherichia coli cells, and that many commonly used fluorescent proteins (FPs) cause severe mislocalization when fused to homo-oligomers. Re-tagging five other reportedly foci-forming proteins with the most monomeric FP tested suggests the foci were caused by the FPs.
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Iber D. Inferring Biological Mechanisms by Data-Based Mathematical Modelling: Compartment-Specific Gene Activation during Sporulation in Bacillus subtilis as a Test Case. Adv Bioinformatics 2012; 2011:124062. [PMID: 22312331 PMCID: PMC3270535 DOI: 10.1155/2011/124062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/12/2011] [Accepted: 11/03/2011] [Indexed: 11/27/2022] Open
Abstract
Biological functionality arises from the complex interactions of simple components. Emerging behaviour is difficult to recognize with verbal models alone, and mathematical approaches are important. Even few interacting components can give rise to a wide range of different responses, that is, sustained, transient, oscillatory, switch-like responses, depending on the values of the model parameters. A quantitative comparison of model predictions and experiments is therefore important to distinguish between competing hypotheses and to judge whether a certain regulatory behaviour is at all possible and plausible given the observed type and strengths of interactions and the speed of reactions. Here I will review a detailed model for the transcription factor σ(F), a regulator of cell differentiation during sporulation in Bacillus subtilis. I will focus in particular on the type of conclusions that can be drawn from detailed, carefully validated models of biological signaling networks. For most systems, such detailed experimental information is currently not available, but accumulating biochemical data through technical advances are likely to enable the detailed modelling of an increasing number of pathways. A major challenge will be the linking of such detailed models and their integration into a multiscale framework to enable their analysis in a larger biological context.
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Affiliation(s)
- Dagmar Iber
- Department for Biosystems Science and Engineering, Switzerland and Swiss Institute of Bioinformatics (SIB), ETH Zurich, Mattenstraße 26, Basel 4058, Switzerland
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Modified mariner transposons for random inducible-expression insertions and transcriptional reporter fusion insertions in Bacillus subtilis. Appl Environ Microbiol 2011; 78:778-85. [PMID: 22113911 DOI: 10.1128/aem.07098-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Transposons are mobile genetic elements bounded by insertion sequences that are recognized by a specific mobilizing transposase enzyme. The transposase may mobilize not only the insertion sequences but also intervening DNA. mariner is a particularly efficient transposon for the random chromosomal integration of genes and insertional mutagenesis. Here, we modify an existing mariner transposon, TnYLB, such that it can easily be genetically manipulated and introduced into Bacillus subtilis. We generate a series of three new mariner derivatives that mobilize spectinomycin, chloramphenicol, and kanamycin antibiotic resistance cassettes. Furthermore, we generate a series of transposons with a strong, outward-oriented, optionally isopropyl-β-D-thiogalactopyranoside (IPTG)-inducible promoter for the random overexpression of neighboring genes and a series of transposons with a promoterless lacZ gene for the random generation of transcriptional reporter fusions. We note that the modification of the base transposon is not restricted to B. subtilis and should be applicable to any mariner-compatible host organism, provided that in vitro mutagenesis or an in vivo species-specific delivery vector is employed.
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26
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Rayo J, Amara N, Krief P, Meijler MM. Live cell labeling of native intracellular bacterial receptors using aniline-catalyzed oxime ligation. J Am Chem Soc 2011; 133:7469-75. [PMID: 21513325 DOI: 10.1021/ja200455d] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Live cell fluorescent labeling of proteins has become a seminal tool in biology and has led to hallmark discoveries in diverse research areas such as protein trafficking, cell-to-cell interactions, and intracellular network dynamics. One of the main challenges, however, remains the ability to label intracellular proteins using fluorescent ligands with high specificity, all the while retaining viability of the targeted cells. Here, we present the first example of live cell labeling and imaging of an intracellular bacterial receptor involved in cell-to-cell communication (i.e., quorum sensing), using a novel two-step approach involving covalent attachment of a reactive mimic of the primary endogenous Pseudomonas aeruginosa quorum-sensing signal to its receptor, LasR, followed by aniline-catalyzed oxime formation between the modified receptor and a fluorescent BODIPY derivative. Our results indicate that LasR is not distributed evenly throughout the cytoplasmic membrane but is instead concentrated at the poles of the P. aeruginosa cell.
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Affiliation(s)
- Josep Rayo
- Department of Chemistry and National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er-Sheva 84105, Israel
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27
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Keiler KC. RNA localization in bacteria. Curr Opin Microbiol 2011; 14:155-9. [PMID: 21354362 DOI: 10.1016/j.mib.2011.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 01/28/2011] [Indexed: 11/24/2022]
Abstract
Bacteria localize proteins and DNA regions to specific subcellular sites, and several recent publications show that RNAs are localized within the cell as well. Localization of tmRNA and some mRNAs indicates that RNAs can be sequestered at specific sites by RNA binding proteins, or can be trapped at the location where they are transcribed. Although the functions of RNA localization are not yet completely understood, it appears that one function of RNA localization is to regulate RNA abundance by controlling access to nucleases. New techniques for visualizing RNAs will likely lead to increased examination of spatial control of RNAs and the role this control plays in the regulation of gene expression and bacterial physiology.
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Affiliation(s)
- Kenneth C Keiler
- Department of Biochemistry and Molecular Biology, Penn State University, 401 Althouse Laboratory, University Park, PA 16802,
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28
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Abstract
Despite their small size, bacteria have a remarkably intricate internal organization. Bacteria deploy proteins and protein complexes to particular locations and do so in a dynamic manner in lockstep with the organized deployment of their chromosome. The dynamic subcellular localization of protein complexes is an integral feature of regulatory processes of bacterial cells.
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Affiliation(s)
- L Shapiro
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
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Chaperone-protease systems in regulation and protein quality control in Bacillus subtilis. Res Microbiol 2009; 160:637-44. [DOI: 10.1016/j.resmic.2009.08.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 08/20/2009] [Accepted: 08/20/2009] [Indexed: 12/13/2022]
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30
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The role of proteolysis in the Caulobacter crescentus cell cycle and development. Res Microbiol 2009; 160:687-95. [PMID: 19781638 DOI: 10.1016/j.resmic.2009.09.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 09/03/2009] [Accepted: 09/04/2009] [Indexed: 11/23/2022]
Abstract
Caulobacter crescentus cell cycle progression is implemented by oscillating global transcriptional regulators that establish temporal and spatial control of modular genetic subsystems during the cell cycle. The hierarchy of this regulatory circuit is established through a combination of gene expression control and regulated proteolysis. Recent results highlight the importance of spatial organization for controlled proteolysis in C. crescentus.
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31
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Abstract
Members of the AAA+ protein superfamily contribute to many diverse aspects of protein homeostasis in prokaryotic cells. As a fundamental component of numerous proteolytic machines in bacteria, AAA+ proteins play a crucial part not only in general protein quality control but also in the regulation of developmental programmes, through the controlled turnover of key proteins such as transcription factors. To manage these many, varied tasks, Hsp100/Clp and AAA+ proteases use specific adaptor proteins to enhance or expand the substrate recognition abilities of their cognate protease. Here, we review our current knowledge of the modulation of bacterial AAA+ proteases by these cellular arbitrators.
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32
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Kobayashi H, De Nisco NJ, Chien P, Simmons LA, Walker GC. Sinorhizobium meliloti CpdR1 is critical for co-ordinating cell cycle progression and the symbiotic chronic infection. Mol Microbiol 2009; 73:586-600. [PMID: 19602145 DOI: 10.1111/j.1365-2958.2009.06794.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: 02/04/2023]
Abstract
ATP-driven proteolysis plays a major role in regulating the bacterial cell cycle, development and stress responses. In the nitro -fixing symbiosis with host plants, Sinorhizobium meliloti undergoes a profound cellular differentiation, including endoreduplication of the ome. The regulatory mechanisms governing the alterations of the S. meliloti cell cycle in planta are largely unknown. Here, we report the characterization of two cpdR homologues, cpdR1 and cpdR2, of S. meliloti that encode single-domain response regulators. In Caulobacter crescentus, CpdR controls the polar localization of the ClpXP protease, thereby mediating the regulated proteolysis of key protein(s), such as CtrA, involved in cell cycle progression. The S. meliloti cpdR1-null mutant can invade the host cytoplasm, however, the intracellular bacteria are unable to differentiate into bacteroids. We show that S. meliloti CpdR1 has a polar localization pattern and a role in ClpX positioning similar to C. crescentus CpdR, suggesting a conserved function of CpdR proteins among alpha-proteobacteria. However, in S. meliloti, free-living cells of the cpdR1-null mutant show a striking morphology of irregular coccoids and aberrant DNA replication. Thus, we demonstrate that CpdR1 mediates the co-ordination of cell cycle events, which are critical for both the free-living cell division and the differentiation required for the chronic intracellular infection.
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Affiliation(s)
- Hajime Kobayashi
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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33
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Controlled destruction: AAA+ ATPases in protein degradation from bacteria to eukaryotes. Curr Opin Struct Biol 2009; 19:209-17. [DOI: 10.1016/j.sbi.2009.02.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2008] [Revised: 02/16/2009] [Accepted: 02/26/2009] [Indexed: 01/11/2023]
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Hahn J, Kramer N, Briley K, Dubnau D. McsA and B mediate the delocalization of competence proteins from the cell poles of Bacillus subtilis. Mol Microbiol 2009; 72:202-15. [PMID: 19226326 DOI: 10.1111/j.1365-2958.2009.06636.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
During the development of transformability (competence), Bacillus subtilis synthesizes a set of proteins that mediate both the uptake of DNA at the cell poles and the recombination of this DNA with the resident chromosome. Most, if not all, of these Com proteins localize to the poles of the cell, where they associate with one another, and are then seen to delocalize as transformability declines. In this study, we use fluorescence microscopy to analyse the localization and delocalization processes. We show that localization most likely occurs by a diffusion-capture mechanism, not requiring metabolic energy, whereas delocalization is prevented in the presence of sodium azide. The kinetics of localization suggest that this process requires the synthesis of a critical protein or set of proteins, which are needed to anchor the Com protein complex to the poles. We further show that the protein kinase proteins McsA and McsB are needed for delocalization, as are ClpP and either of the AAA(+) (ATPases associated with a variety of cellular activities) proteins ClpC or ClpE. Of these proteins, at least McsB, ClpC and ClpP localize to the cell poles of competent cells. Our evidence strongly suggests that delocalization depends on the degradation of the postulated anchor protein(s) by the McsA-McsB-(ClpC or ClpE)-ClpP protease in an ATP-dependent process that involves the autophosphorylation of McsB. The extent of cell-pole association at any given time reflects the relative rates of localization and delocalization. The kinetics of this dynamic process differs for individual Com proteins, with the DNA-binding proteins SsbB and DprA exhibiting less net localization.
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Affiliation(s)
- Jeanette Hahn
- Public Health Research Institute, University of Medicine and Dentistry of New Jersey, Newark, NJ, USA
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35
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Clp and Lon proteases occupy distinct subcellular positions in Bacillus subtilis. J Bacteriol 2008; 190:6758-68. [PMID: 18689473 DOI: 10.1128/jb.00590-08] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among other functions, ATP-dependent proteases degrade misfolded proteins and remove several key regulatory proteins necessary to activate stress responses. In Bacillus subtilis, ClpX, ClpE, and ClpC form homohexameric ATPases that couple to the ClpP peptidase. To understand where these peptidases and ATPases localize in living cells, each protein was fused to a fluorescent moiety. We found that ClpX-GFP (green fluorescent protein) and ClpP-GFP localized as focal assemblies in areas that were not occupied by the nucleoid. We found that the percentage of cells with ClpP-GFP foci increased following heat shock independently of protein synthesis. We determined that ClpE-YFP (yellow fluorescent protein) and ClpC-YFP formed foci coincident with nucleoid edges, usually near cell poles. Furthermore, we found that ClpQ-YFP (HslV) localized as small foci, usually positioned near the cell membrane. We found that ClpQ-YFP foci were dependent on the presence of the cognate hexameric ATPase ClpY (HslU). Moreover, we found that LonA-GFP is coincident with the nucleoid during normal growth and that LonA-GFP also localized to the forespore during development. We also investigated LonB-GFP and found that this protein localized to the forespore membrane early in development, followed by localization throughout the forespore later in development. Our comprehensive study has shown that in B. subtilis several ATP-fueled proteases occupy distinct subcellular locations. With these data, we suggest that substrate specificity could be determined, in part, by the spatial and temporal organization of proteases in vivo.
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