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Ba X, Matuszewska M, Kalmar L, Fan J, Zou G, Corander D, Raisen CL, Li S, Li L, Weinert LA, Tucker AW, Grant AJ, Zhou R, Holmes MA. High-Throughput Mutagenesis Reveals a Role for Antimicrobial Resistance- and Virulence-Associated Mobile Genetic Elements in Staphylococcus aureus Host Adaptation. Microbiol Spectr 2023; 11:e0421322. [PMID: 36815781 PMCID: PMC10101091 DOI: 10.1128/spectrum.04213-22] [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: 10/18/2022] [Accepted: 02/01/2023] [Indexed: 02/24/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) clonal-complex 398 (CC398) is the dominant livestock-associated (LA) MRSA lineage in European livestock and an increasing cause of difficult-to-treat human disease. LA-CC398 MRSA evolved from a diverse human-associated methicillin-sensitive population, and this transition from humans to livestock was associated with three mobile genetic elements (MGEs). In this study, we apply transposon-directed insertion site sequencing (TraDIS), a high-throughput transposon mutagenesis approach, to investigate genetic signatures that contribute to LA-CC398 causing disease in humans. We identified 26 genes associated with LA-CC398 survival in human blood and 47 genes in porcine blood. We carried out phylogenetic reconstruction on 1,180 CC398 isolates to investigate the genetic context of all identified genes. We found that all genes associated with survival in human blood were part of the CC398 core genome, while 2/47 genes essential for survival in porcine blood were located on MGEs. Gene SAPIG0966 was located on the previously identified Tn916 transposon carrying a tetracycline resistance gene, which has been shown to be stably inherited within LA-CC398. Gene SAPIG1525 was carried on a phage element, which in part, matched phiSa2wa_st1, a previously identified bacteriophage carrying the Panton-Valentine leucocidin (PVL) virulence factor. Gene deletion mutants constructed in two LA-CC398 strains confirmed that the SAPIG0966 carrying Tn916 and SAPIG1525 were important for CC398 survival in porcine blood. Our study shows that MGEs that carry antimicrobial resistance and virulence genes could have a secondary function in bacterial survival in blood and may be important for host adaptation. IMPORTANCE CC398 is the dominant type of methicillin-resistant Staphylococcus aureus (MRSA) in European livestock and a growing cause of human infections. Previous studies have suggested MRSA CC398 evolved from human-associated methicillin-sensitive Staphylococcus aureus and is capable of rapidly readapting to human hosts while maintaining antibiotic resistance. Using high-throughput transposon mutagenesis, our study identified 26 and 47 genes important for MRSA CC398 survival in human and porcine blood, respectively. Two of the genes important for MRSA CC398 survival in porcine blood were located on mobile genetic elements (MGEs) carrying resistance or virulence genes. Our study shows that these MGEs carrying antimicrobial resistance and virulence genes could have a secondary function in bacterial survival in blood and may be important for blood infection and host adaptation.
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Affiliation(s)
- Xiaoliang Ba
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Marta Matuszewska
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Lajos Kalmar
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Jingyan Fan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University College of Veterinary Medicine, Wuhan, China
| | - Geng Zou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University College of Veterinary Medicine, Wuhan, China
| | - Desirée Corander
- Department of Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Claire L. Raisen
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Shaowen Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University College of Veterinary Medicine, Wuhan, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University College of Veterinary Medicine, Wuhan, China
- Cooperative Innovation Centre of Sustainable Pig Production, Wuhan, China
- International Research Centre for Animal Diseases (MOST), Wuhan, China
| | - Lucy A. Weinert
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Alexander W. Tucker
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Andrew J. Grant
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University College of Veterinary Medicine, Wuhan, China
- Cooperative Innovation Centre of Sustainable Pig Production, Wuhan, China
- International Research Centre for Animal Diseases (MOST), Wuhan, China
| | - Mark A. Holmes
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
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Saaki TNV, Teng Z, Wenzel M, Ventroux M, Carballido-Lόpez R, Noirot-Gros MF, Hamoen LW. SepF supports the recruitment of the DNA translocase SftA to the Z-ring. Mol Microbiol 2022; 117:1263-1274. [PMID: 35411648 PMCID: PMC9320952 DOI: 10.1111/mmi.14906] [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: 12/02/2021] [Revised: 04/07/2022] [Accepted: 04/09/2022] [Indexed: 11/28/2022]
Abstract
In many bacteria, cell division begins before the sister chromosomes are fully segregated. Specific DNA translocases ensure that the chromosome is removed from the closing septum, such as the transmembrane protein FtsK in Escherichia coli. Bacillus subtilis contains two FtsK homologues, SpoIIIE and SftA. SftA is active during vegetative growth whereas SpoIIIE is primarily active during sporulation and pumps the chromosome into the spore compartment. FtsK and SpoIIIE contain several transmembrane helices, however SftA is assumed to be a cytoplasmic protein. It is unknown how SftA is recruited to the cell division site. Here we show that SftA is a peripheral membrane protein, containing an N-terminal amphipathic helix that reversibly anchors the protein to the cell membrane. Using a yeast two-hybrid screen we found that SftA interacts with the conserved cell division protein SepF. Based on extensive genetic analyses and previous data we propose that the septal localization of SftA depends on either SepF or the cell division protein FtsA. Since SftA seems to interfere with the activity of SepF, and since inactivation of SepF mitigates the sensitivity of a ∆sftA mutant for ciprofloxacin, we speculate that SftA might delay septum synthesis when chromosomal DNA is in the vicinity.
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Affiliation(s)
- Terrens N V Saaki
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - Zihao Teng
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - Michaela Wenzel
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands.,current address: Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Magali Ventroux
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay Jouy-en-Josas, France
| | - Rut Carballido-Lόpez
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay Jouy-en-Josas, France
| | | | - Leendert W Hamoen
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
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Chan H, Mohamed AMT, Grainge I, Rodrigues CDA. FtsK and SpoIIIE, coordinators of chromosome segregation and envelope remodeling in bacteria. Trends Microbiol 2021; 30:480-494. [PMID: 34728126 DOI: 10.1016/j.tim.2021.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 10/05/2021] [Accepted: 10/06/2021] [Indexed: 10/19/2022]
Abstract
The translocation of DNA during bacterial cytokinesis is mediated by the SpoIIIE/FtsK family of proteins. These proteins ensure efficient chromosome segregation into sister cells by ATP-driven translocation of DNA and they control chromosome dimer resolution. How FtsK/SpoIIIE mediate chromosome translocation during cytokinesis in Gram-positive and Gram-negative organisms has been the subject of debate. Studies on FtsK in Escherichia coli, and recent work on SpoIIIE in Bacillus subtilis, have identified interactions between each translocase and the division machinery, supporting the idea that SpoIIIE and FtsK coordinate the final steps of cytokinesis with completion of chromosome segregation. Here we summarize and discuss the view that SpoIIIE and FtsK play similar roles in coordinating cytokinesis with chromosome segregation, during growth and differentiation.
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Affiliation(s)
- Helena Chan
- iThree Institute, University of Technology, Sydney, NSW, Australia
| | | | - Ian Grainge
- School of Environmental and Life Sciences, University of Newcastle, NSW, Australia.
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4
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Wu LJ, Lee S, Park S, Eland LE, Wipat A, Holden S, Errington J. Geometric principles underlying the proliferation of a model cell system. Nat Commun 2020; 11:4149. [PMID: 32811832 PMCID: PMC7434903 DOI: 10.1038/s41467-020-17988-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/24/2020] [Indexed: 02/07/2023] Open
Abstract
Many bacteria can form wall-deficient variants, or L-forms, that divide by a simple mechanism that does not require the FtsZ-based cell division machinery. Here, we use microfluidic systems to probe the growth, chromosome cycle and division mechanism of Bacillus subtilis L-forms. We find that forcing cells into a narrow linear configuration greatly improves the efficiency of cell growth and chromosome segregation. This reinforces the view that L-form division is driven by an excess accumulation of surface area over volume. Cell geometry also plays a dominant role in controlling the relative positions and movement of segregating chromosomes. Furthermore, the presence of the nucleoid appears to influence division both via a cell volume effect and by nucleoid occlusion, even in the absence of FtsZ. Our results emphasise the importance of geometric effects for a range of crucial cell functions, and are of relevance for efforts to develop artificial or minimal cell systems.
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Affiliation(s)
- Ling Juan Wu
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
| | - Seoungjun Lee
- grid.1006.70000 0001 0462 7212Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX UK ,grid.13097.3c0000 0001 2322 6764Present Address: Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, SE5 9RX UK
| | - Sungshic Park
- grid.1006.70000 0001 0462 7212Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX UK ,grid.1006.70000 0001 0462 7212Interdisciplinary Computing and Complex BioSystems research group, School of Computing, Newcastle University, Newcastle upon Tyne, NE4 5TG UK
| | - Lucy E. Eland
- grid.1006.70000 0001 0462 7212Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX UK ,grid.1006.70000 0001 0462 7212Interdisciplinary Computing and Complex BioSystems research group, School of Computing, Newcastle University, Newcastle upon Tyne, NE4 5TG UK
| | - Anil Wipat
- grid.1006.70000 0001 0462 7212Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX UK ,grid.1006.70000 0001 0462 7212Interdisciplinary Computing and Complex BioSystems research group, School of Computing, Newcastle University, Newcastle upon Tyne, NE4 5TG UK
| | - Séamus Holden
- grid.1006.70000 0001 0462 7212Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX UK
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Biosciences Institute, Medical School, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
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Single-Molecule Tracking of DNA Translocases in Bacillus subtilis Reveals Strikingly Different Dynamics of SftA, SpoIIIE, and FtsA. Appl Environ Microbiol 2018; 84:AEM.02610-17. [PMID: 29439991 DOI: 10.1128/aem.02610-17] [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: 11/22/2017] [Accepted: 01/30/2018] [Indexed: 11/20/2022] Open
Abstract
Like many bacteria, Bacillus subtilis possesses two DNA translocases that affect chromosome segregation at different steps. Prior to septum closure, nonsegregated DNA is moved into opposite cell halves by SftA, while septum-entrapped DNA is rescued by SpoIIIE. We have used single-molecule fluorescence microscopy and tracking (SMT) experiments to describe the dynamics of the two different DNA translocases, the cell division protein FtsA and the glycolytic enzyme phosphofructokinase (PfkA), in real time. SMT revealed that about 30% of SftA molecules move through the cytosol, while a fraction of 70% is septum bound and static. In contrast, only 35% of FtsA molecules are static at midcell, while SpoIIIE molecules diffuse within the membrane and show no enrichment at the septum. Several lines of evidence suggest that FtsA plays a role in septal recruitment of SftA: an ftsA deletion results in a significant reduction in septal SftA recruitment and a decrease in the average dwell time of SftA molecules. FtsA can recruit SftA to the membrane in a heterologous eukaryotic system, suggesting that SftA may be partially recruited via FtsA. Therefore, SftA is a component of the division machinery, while SpoIIIE is not, and it is otherwise a freely diffusive cytosolic enzyme in vivo Our developed SMT script is a powerful technique to determine if low-abundance proteins are membrane bound or cytosolic, to detect differences in populations of complex-bound and unbound/diffusive proteins, and to visualize the subcellular localization of slow- and fast-moving molecules in live cells.IMPORTANCE DNA translocases couple the late events of chromosome segregation to cell division and thereby play an important role in the bacterial cell cycle. The proteins fall into one of two categories, integral membrane translocases or nonintegral translocases. We show that the membrane-bound translocase SpoIIIE moves slowly throughout the cell membrane in B. subtilis and does not show a clear association with the division septum, in agreement with the idea that it binds membrane-bound DNA, which can occur through cell division across nonsegregated chromosomes. In contrast, SftA behaves like a soluble protein and is recruited to the division septum as a component of the division machinery. We show that FtsA contributes to the recruitment of SftA, revealing a dual role of FtsA at the division machinery, but it is not the only factor that binds SftA. Our work represents a detailed in vivo study of DNA translocases at the single-molecule level.
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6
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Gao Y, Wenzel M, Jonker MJ, Hamoen LW. Free SepF interferes with recruitment of late cell division proteins. Sci Rep 2017; 7:16928. [PMID: 29209072 PMCID: PMC5717166 DOI: 10.1038/s41598-017-17155-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/16/2017] [Indexed: 12/24/2022] Open
Abstract
The conserved cell division protein SepF aligns polymers of FtsZ, the key cell division protein in bacteria, during synthesis of the (Fts)Z-ring at midcell, the first stage in cytokinesis. In addition, SepF acts as a membrane anchor for the Z-ring. Recently, it was shown that SepF overexpression in Mycobacterium smegmatis blocks cell division. Why this is the case is not known. Surprisingly, we found in Bacillus subtilis that SepF overproduction does not interfere with Z-ring assembly, but instead blocks assembly of late division proteins responsible for septum synthesis. Transposon mutagenesis suggested that SepF overproduction suppresses the essential WalRK two-component system, which stimulates expression of ftsZ. Indeed, it emerged that SepF overproduction impairs normal WalK localization. However, transcriptome analysis showed that the WalRK activity was in fact not reduced in SepF overexpressing cells. Further experiments indicated that SepF competes with EzrA and FtsA for binding to FtsZ, and that binding of extra SepF by FtsZ alleviates the cell division defect. This may explain why activation of WalRK in the transposon mutant, which increases ftsZ expression, counteracts the division defect. In conclusion, our data shows that an imbalance in early cell division proteins can interfere with recruitment of late cell division proteins.
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Affiliation(s)
- Yongqiang Gao
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Michaela Wenzel
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Martijs J Jonker
- MicroArray Department and Integrative Bioinformatics Unit, Swammerdam Institute for Life Sciences, University of Amsterdam, Sciencepark 904, 1098 XH, Amsterdam, The Netherlands
| | - Leendert W Hamoen
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
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7
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Castillo F, Benmohamed A, Szatmari G. Xer Site Specific Recombination: Double and Single Recombinase Systems. Front Microbiol 2017; 8:453. [PMID: 28373867 PMCID: PMC5357621 DOI: 10.3389/fmicb.2017.00453] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/03/2017] [Indexed: 12/20/2022] Open
Abstract
The separation and segregation of newly replicated bacterial chromosomes can be constrained by the formation of circular chromosome dimers caused by crossing over during homologous recombination events. In Escherichia coli and most bacteria, dimers are resolved to monomers by site-specific recombination, a process performed by two Chromosomally Encoded tyrosine Recombinases (XerC and XerD). XerCD recombinases act at a 28 bp recombination site dif, which is located at the replication terminus region of the chromosome. The septal protein FtsK controls the initiation of the dimer resolution reaction, so that recombination occurs at the right time (immediately prior to cell division) and at the right place (cell division septum). XerCD and FtsK have been detected in nearly all sequenced eubacterial genomes including Proteobacteria, Archaea, and Firmicutes. However, in Streptococci and Lactococci, an alternative system has been found, composed of a single recombinase (XerS) genetically linked to an atypical 31 bp recombination site (difSL). A similar recombination system has also been found in 𝜀-proteobacteria such as Campylobacter and Helicobacter, where a single recombinase (XerH) acts at a resolution site called difH. Most Archaea contain a recombinase called XerA that acts on a highly conserved 28 bp sequence dif, which appears to act independently of FtsK. Additionally, several mobile elements have been found to exploit the dif/Xer system to integrate their genomes into the host chromosome in Vibrio cholerae, Neisseria gonorrhoeae, and Enterobacter cloacae. This review highlights the versatility of dif/Xer recombinase systems in prokaryotes and summarizes our current understanding of homologs of dif/Xer machineries.
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Affiliation(s)
- Fabio Castillo
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, MontréalQC, Canada
| | | | - George Szatmari
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, MontréalQC, Canada
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El Najjar N, Kaimer C, Rösch T, Graumann PL. Requirements for Septal Localization and Chromosome Segregation Activity of the DNA Translocase SftA from Bacillus subtilis. J Mol Microbiol Biotechnol 2017; 27:29-42. [PMID: 28110333 DOI: 10.1159/000450725] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/09/2016] [Indexed: 11/19/2022] Open
Abstract
Bacillus subtilis possesses 2 DNA translocases that affect late stages of chromosome segregation: SftA separates nonsegregated DNA prior to septum closure, while SpoIIIE rescues septum-entrapped DNA. We provide evidence that SftA is associated with the division machinery via a stretch of 47 amino acids within its N-terminus, suggesting that SftA is recruited by protein-protein interactions with a component of the division machinery. SftA was also recruited to mid-cell in the absence of its first 20 amino acids, which are proposed to contain a membrane-binding motif. Cell fractionation experiments showed that SftA can be found in the cytosolic fraction, and to a minor degree in the membrane fraction, showing that it is a soluble protein in vivo. The expression of truncated SftA constructs led to a dominant sftA deletion phenotype, even at very low induction rates of the truncated proteins, indicating that the incorporation of nonfunctional monomers into SftA hexamers abolishes functionality. Mobility shift experiments and surface plasmon binding studies showed that SftA binds to DNA in a cooperative manner, and demonstrated low ATPase activity when binding to short nucleotides rather than to long stretches of DNA.
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Affiliation(s)
- Nina El Najjar
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, and Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
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Veiga H, G Pinho M. Staphylococcus aureus requires at least one FtsK/SpoIIIE protein for correct chromosome segregation. Mol Microbiol 2016; 103:504-517. [PMID: 27886417 DOI: 10.1111/mmi.13572] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2016] [Indexed: 11/30/2022]
Abstract
Faithful coordination between bacterial cell division and chromosome segregation in rod-shaped bacteria, such as Escherichia coli and Bacillus subtilis, is dependent on the DNA translocase activity of FtsK/SpoIIIE proteins, which move DNA away from the division site before cytokinesis is completed. However, the role of these proteins in chromosome partitioning has not been well studied in spherical bacteria. Here, it was shown that the two Staphylococcus aureus FtsK/SpoIIIE homologues, SpoIIIE and FtsK, operate in independent pathways to ensure correct chromosome management during cell division. SpoIIIE forms foci at the centre of the closing septum in at least 50% of the cells that are close to complete septum synthesis. FtsK is a multifunctional septal protein with a C-terminal DNA translocase domain that is not required for correct chromosome management in the presence of SpoIIIE. However, lack of both SpoIIIE and FtsK causes severe nucleoid segregation and morphological defects, showing that the two proteins have partially redundant roles in S. aureus.
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Affiliation(s)
- Helena Veiga
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Mariana G Pinho
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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Defeu Soufo HJ. A Novel Cell Type Enables B. subtilis to Escape from Unsuccessful Sporulation in Minimal Medium. Front Microbiol 2016; 7:1810. [PMID: 27891124 PMCID: PMC5104909 DOI: 10.3389/fmicb.2016.01810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 10/27/2016] [Indexed: 11/28/2022] Open
Abstract
Sporulation is the most enduring survival strategy developed by several bacterial species. However, spore development of the model organism Bacillus subtilis has mainly been studied by means of media or conditions optimized for the induction of sporogenesis. Here, I show that during prolonged growth during stationary phase in minimal medium, B. subtilis undergoes an asymmetric cell division that produces small and round-shaped, DNA containing cells. In contrast to wild-type cells, mutants harboring spo0A or spoIIIE/sftA double mutations neither sporulate nor produce this special cell type, providing evidence that the small round cells emerge from the abortion of endospore formation. In most cases observed, the small round cells arise in the presence of sigma H but absence of sigma F activity, different from cases of abortive sporulation described for rich media. These data suggest that in minimal media, many cells are able to initiate but fail to complete spore development, and therefore return to normal growth as rods. This work reveals that the continuation of asymmetric cell division, which results in the formation of the small round cells, is a way for cells to delay or escape from—unsuccessful—sporulation. Based on these findings, I suggest to name the here described cell type as “dwarf cells” to distinguish them from the well-known minicells observed in mutants defective in septum placement or proper chromosome partitioning.
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11
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Xer Site-Specific Recombination: Promoting Vertical and Horizontal Transmission of Genetic Information. Microbiol Spectr 2016; 2. [PMID: 26104463 DOI: 10.1128/microbiolspec.mdna3-0056-2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Two related tyrosine recombinases, XerC and XerD, are encoded in the genome of most bacteria where they serve to resolve dimers of circular chromosomes by the addition of a crossover at a specific site, dif. From a structural and biochemical point of view they belong to the Cre resolvase family of tyrosine recombinases. Correspondingly, they are exploited for the resolution of multimers of numerous plasmids. In addition, they are exploited by mobile DNA elements to integrate into the genome of their host. Exploitation of Xer is likely to be advantageous to mobile elements because the conservation of the Xer recombinases and of the sequence of their chromosomal target should permit a quite easy extension of their host range. However, it requires means to overcome the cellular mechanisms that normally restrict recombination to dif sites harbored by a chromosome dimer and, in the case of integrative mobile elements, to convert dedicated tyrosine resolvases into integrases.
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12
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Adams DW, Wu LJ, Errington J. Cell cycle regulation by the bacterial nucleoid. Curr Opin Microbiol 2015; 22:94-101. [PMID: 25460802 PMCID: PMC4726725 DOI: 10.1016/j.mib.2014.09.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/29/2014] [Accepted: 09/30/2014] [Indexed: 12/17/2022]
Abstract
Nucleoid occlusion prevents cell division over the bacterial chromosome. Nucleoid occlusion factors identified in B. subtilis, E. coli and S. aureus. Noc and SlmA are sequence specific DNA-binding proteins. They both act as spatial and temporal regulators of cell division. Using some basic general principles bacteria employ diverse regulatory mechanisms.
Division site selection presents a fundamental challenge to all organisms. Bacterial cells are small and the chromosome (nucleoid) often fills most of the cell volume. Thus, in order to maximise fitness and avoid damaging the genetic material, cell division must be tightly co-ordinated with chromosome replication and segregation. To achieve this, bacteria employ a number of different mechanisms to regulate division site selection. One such mechanism, termed nucleoid occlusion, allows the nucleoid to protect itself by acting as a template for nucleoid occlusion factors, which prevent Z-ring assembly over the DNA. These factors are sequence-specific DNA-binding proteins that exploit the precise organisation of the nucleoid, allowing them to act as both spatial and temporal regulators of bacterial cell division. The identification of proteins responsible for this process has provided a molecular understanding of nucleoid occlusion but it has also prompted the realisation that substantial levels of redundancy exist between the diverse systems that bacteria employ to ensure that division occurs in the right place, at the right time.
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Affiliation(s)
- David William Adams
- Centre for Bacterial Cell Biology, Baddiley-Clark Building, Medical School, Newcastle University, Richardson Road, Newcastle Upon Tyne, NE2 4AX, United Kingdom
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13
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PprA, a pleiotropic protein for radioresistance, works through DNA gyrase and shows cellular dynamics during postirradiation recovery in Deinococcus radiodurans. J Genet 2015; 93:349-54. [PMID: 25189229 DOI: 10.1007/s12041-014-0382-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PprA, a pleiotropic protein involved in radioresistance of Deinococcus radiodurans was detected in multiprotein DNA processing complex identified from this bacterium. pprA mutant expressing GFP-PprA could restore its wild type resistance of γ radiation. Under normal conditions, GFP-PprA expressing cells showed PprA localization on both septum trapped nucleoids (STN) and nucleoids located elsewhere (MCN). Cell exposed to 4 kGy γ radiation showed nearly 2 h growth lag and during this growth arrest phase, the majority of the cells had GFP-PprA located on MCN. While in late phase (~120 min) PIR cells, when cells are nearly out of growth arrest, PprA was maximally found with STN. These cells when treated with nalidixic acid showed diffused localization of PprA across the septum. gyrA disruption mutant of D. radiodurans showed growth inhibition, which increased further in gyrA pprA mutant. Interestingly, gyrA mutant showed ~20-fold less resistance to γ radiation as compared to wild type, which did increase further in gyrA pprA mutant. These results suggested that PprA localization undergoes a dynamic change during PIR, and its localization on nucleoid near septum and functional interaction with gyrase A might suggest a mechanism that could explain PprA role in genome segregation possibly through topoisomerase II.
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Kleine Borgmann LAK, Graumann PL. Structural maintenance of chromosome complex in bacteria. J Mol Microbiol Biotechnol 2015; 24:384-95. [PMID: 25732340 DOI: 10.1159/000368931] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In all organisms, from eukaryotes to prokaryotes, the chromosome is highly compacted and organized. Chromosome condensation is essential in all cells and ranges from 1,000- to more than 10,000-fold between bacterial and eukaryotic cells. Replication and transcription occur in parallel with chromosome segregation in bacteria. Structural maintenance of chromosome proteins play a key role in chromosome compaction and segregation, their coordination with the cell cycle, and in various other chromosome dynamics, including DNA repair. In spite of their essential nature in almost all organisms, their function at a molecular level is only slowly beginning to emerge.
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Affiliation(s)
- Luise A K Kleine Borgmann
- Division of Biological Sciences and Section of Molecular Biology, University of California, San Diego, La Jolla, Calif., USA
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Crozat E, Rousseau P, Fournes F, Cornet F. The FtsK family of DNA translocases finds the ends of circles. J Mol Microbiol Biotechnol 2015; 24:396-408. [PMID: 25732341 DOI: 10.1159/000369213] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A global view of bacterial chromosome choreography during the cell cycle is emerging, highlighting as a next challenge the description of the molecular mechanisms and factors involved. Here, we review one such factor, the FtsK family of DNA translocases. FtsK is a powerful and fast translocase that reads chromosome polarity. It couples segregation of the chromosome with cell division and controls the last steps of segregation in time and space. The second model protein of the family SpoIIIE acts in the transfer of the Bacillus subtilis chromosome during sporulation. This review focuses on the molecular mechanisms used by FtsK and SpoIIIE to segregate chromosomes with emphasis on the latest advances and open questions.
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Affiliation(s)
- Estelle Crozat
- Laboratoire de Microbiologie et de Génétique Moléculaires, CNRS, and Université de Toulouse, Université Paul Sabatier, Toulouse, France
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Bordeleau E, Ghinet MG, Burrus V. Diversity of integrating conjugative elements in actinobacteria: Coexistence of two mechanistically different DNA-translocation systems. Mob Genet Elements 2014; 2:119-124. [PMID: 22934248 PMCID: PMC3429521 DOI: 10.4161/mge.20498] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Conjugation is certainly the most widespread and promiscuous mechanism of horizontal gene transfer in bacteria. During conjugation, DNA translocation across membranes of two cells forming a mating pair is mediated by two types of mobile genetic elements: conjugative plasmids and integrating conjugative elements (ICEs). The vast majority of conjugative plasmids and ICEs employ a sophisticated protein secretion apparatus called type IV secretion system to transfer to a recipient cell. Yet another type of conjugative DNA translocation machinery exists and to date appears to be unique to conjugative plasmids and ICEs of the Actinomycetales order, a sub-group of high G + C Gram-positive bacteria. This conjugative system is reminiscent of the machinery that allows segregation of chromosomal DNA during bacterial cell division and sporulation, and relies on a single FtsK-homolog protein to translocate double-stranded DNA molecules to the recipient cell. Recent thorough sequence analyses reveal that while this latter strategy appears to be used by the majority of ICEs in Actinomycetales, the former is also predicted to be important in exchange of genetic material in actinobacteria.
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Affiliation(s)
- Eric Bordeleau
- Département de biologie; Faculté des sciences; Université de Sherbrooke; QC, Canada
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Cavalier-Smith T. The neomuran revolution and phagotrophic origin of eukaryotes and cilia in the light of intracellular coevolution and a revised tree of life. Cold Spring Harb Perspect Biol 2014; 6:a016006. [PMID: 25183828 PMCID: PMC4142966 DOI: 10.1101/cshperspect.a016006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Three kinds of cells exist with increasingly complex membrane-protein targeting: Unibacteria (Archaebacteria, Posibacteria) with one cytoplasmic membrane (CM); Negibacteria with a two-membrane envelope (inner CM; outer membrane [OM]); eukaryotes with a plasma membrane and topologically distinct endomembranes and peroxisomes. I combine evidence from multigene trees, palaeontology, and cell biology to show that eukaryotes and archaebacteria are sisters, forming the clade neomura that evolved ~1.2 Gy ago from a posibacterium, whose DNA segregation and cell division were destabilized by murein wall loss and rescued by the evolving novel neomuran endoskeleton, histones, cytokinesis, and glycoproteins. Phagotrophy then induced coevolving serial major changes making eukaryote cells, culminating in two dissimilar cilia via a novel gliding-fishing-swimming scenario. I transfer Chloroflexi to Posibacteria, root the universal tree between them and Heliobacteria, and argue that Negibacteria are a clade whose OM, evolving in a green posibacterium, was never lost.
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The presence of conjugative plasmid pLS20 affects global transcription of Its Bacillus subtilis host and confers beneficial stress resistance to cells. Appl Environ Microbiol 2013; 80:1349-58. [PMID: 24334659 DOI: 10.1128/aem.03154-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Conjugation activity of plasmid pLS20 from Bacillus subtilis subsp. natto is induced when cells are diluted into fresh medium and diminishes as cells enter into stationary-phase growth. Transcriptional profiling shows that during mid-exponential growth, more than 5% of the host genes are affected in the presence of the plasmid, in contrast to the minor changes seen in freshly diluted and stationary-phase cells. Changes occurred in many metabolic pathways, although pLS20 does not confer any detectable burden on its host cell, as well as in membrane and cell wall-associated processes, in the large motility operon, and in several other cellular processes. In agreement with these changes, we found considerable alterations in motility and enzyme activity and increased resistance against several different forms of stress in cells containing the plasmid, revealing that the presence of pLS20 has a broad impact on the physiology of its host cell and increases its stress resistance in multiple aspects. Additionally, we found that the lack of chromosomal gene yueB, known to encode a phage receptor protein, which is upregulated in cells containing pLS20, strongly reduced conjugation efficiency, revealing that pLS20 not only increases fitness of its host but also employs host proteins for efficient transfer into a new cell.
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Nolivos S, Sherratt D. The bacterial chromosome: architecture and action of bacterial SMC and SMC-like complexes. FEMS Microbiol Rev 2013; 38:380-92. [PMID: 24118085 PMCID: PMC4255302 DOI: 10.1111/1574-6976.12045] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/09/2013] [Accepted: 08/26/2013] [Indexed: 12/27/2022] Open
Abstract
Structural Maintenance of Chromosomes (SMC) protein complexes are found in all three domains of life. They are characterized by a distinctive and conserved architecture in which a globular ATPase ‘head’ domain is formed by the N- and C-terminal regions of the SMC protein coming together, with a c. 50-nm-long antiparallel coiled-coil separating the head from a dimerization ‘hinge’. Dimerization gives both V- and O-shaped SMC dimers. The distinctive architecture points to a conserved biochemical mechanism of action. However, the details of this mechanism are incomplete, and the precise ways in which this mechanism leads to the biological functions of these complexes in chromosome organization and processing remain unclear. In this review, we introduce the properties of bacterial SMC complexes, compare them with eukaryotic complexes and discuss how their likely biochemical action relates to their roles in chromosome organization and segregation.
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Affiliation(s)
- Sophie Nolivos
- Department of Biochemistry, University of Oxford, Oxford, UK
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Fredriksen L, Moen A, Adzhubei AA, Mathiesen G, Eijsink VGH, Egge-Jacobsen W. Lactobacillus plantarum WCFS1 O-linked protein glycosylation: an extended spectrum of target proteins and modification sites detected by mass spectrometry. Glycobiology 2013; 23:1439-51. [PMID: 24000282 DOI: 10.1093/glycob/cwt071] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
It has recently been shown that the major autolysin Acm2 from Lactobacillus plantarum WCFS1 undergoes intracellular O-GlcNAcylation [Fredriksen L, Mathiesen G, Moen A, Bron PA, Kleerebezem M, Eijsink VG, Egge-Jacobsen W. 2012. The major autolysin Acm2 from Lactobacillus plantarum undergoes cytoplasmic O-glycosylation. J Bacteriol. 194(2):325-333]. To gain more insight into the occurrence of this protein modification, methods based on the higher energy collisional fragmentation of the Orbitrap XL mass spectrometer to generate both diagnostic oxonium (glycan) ions and significant peptide sequencing information were used to detect and identify novel glycoproteins. This led to the identification of 10 novel glycoproteins, including four proteins with well-known functions in the cytoplasm, a compartment not previously recognized to contain glycosylated proteins in bacteria: the molecular chaperone DnaK, the E2 subunit of the pyruvate dehydrogenase complex PdhC, the signal recognition particle receptor FtsY and the DNA translocase FtsK1. Among the other, glycosylated proteins were two extracellular peptidoglycan hydrolases and a mucus-binding protein. In total, 49 glycosylation sites for N-acetylhexosamine (HexNAc) were detected in the 11 Lactobacillus glycoproteins found so far. Most of the attached glycans consisted of a single HexNAc per site, whereas hexose moieties were also found in a few cases (in both of the peptidoglycan hydrolases and in DnaK).
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Affiliation(s)
- Lasse Fredriksen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Aas, Norway
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21
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Natale P, Pazos M, Vicente M. TheEscherichia colidivisome: born to divide. Environ Microbiol 2013; 15:3169-82. [DOI: 10.1111/1462-2920.12227] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/18/2013] [Accepted: 07/23/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Paolo Natale
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
| | - Manuel Pazos
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
| | - Miguel Vicente
- Centro Nacional de Biotecnología (CNB-CSIC); C/Darwin n° 3 E-28049 Madrid Spain
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22
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Pereira AR, Reed P, Veiga H, Pinho MG. The Holliday junction resolvase RecU is required for chromosome segregation and DNA damage repair in Staphylococcus aureus. BMC Microbiol 2013; 13:18. [PMID: 23356868 PMCID: PMC3584850 DOI: 10.1186/1471-2180-13-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 01/17/2013] [Indexed: 11/24/2022] Open
Abstract
Background The Staphylococcus aureus RecU protein is homologous to a Bacillus subtilis Holliday junction resolvase. Interestingly, RecU is encoded in the same operon as PBP2, a penicillin-binding protein required for cell wall synthesis and essential for the full expression of resistance in Methicillin Resistant S. aureus strains. In this work we have studied the role of RecU in the clinical pathogen S. aureus. Results Depletion of RecU in S. aureus results in the appearance of cells with compact nucleoids, septa formed over the DNA and anucleate cells. RecU-depleted cells also show increased septal recruitment of the DNA translocase SpoIIIE, presumably to resolve chromosome segregation defects. Additionally cells are more sensitive to DNA damaging agents such as mitomycin C or UV radiation. Expression of RecU from the ectopic chromosomal spa locus showed that co-expression of RecU and PBP2 was not necessary to ensure correct cell division, a process that requires tight coordination between chromosome segregation and septal cell wall synthesis. Conclusions RecU is required for correct chromosome segregation and DNA damage repair in S. aureus. Co-expression of recU and pbp2 from the same operon is not required for normal cell division.
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Affiliation(s)
- Ana R Pereira
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av, da República, Oeiras 2780-157, Portugal
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Demarre G, Galli E, Barre FX. The FtsK Family of DNA Pumps. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 767:245-62. [PMID: 23161015 DOI: 10.1007/978-1-4614-5037-5_12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Interest for proteins of the FtsK family initially arose from their implication in many primordial processes in which DNA needs to be transported from one cell compartment to another in eubacteria. In the first section of this chapter, we address a list of the cellular functions of the different members of the FtsK family that have been so far studied. Soon after their discovery, interest for the FstK proteins spread because of their unique biochemical properties: most DNA transport systems rely on the assembly of complex multicomponent machines. In contrast, six FtsK proteins are sufficient to assemble into a fast and powerful DNA pump; the pump transports closed circular double stranded DNA molecules without any covalent-bond breakage nor topological alteration; transport is oriented despite the intrinsic symmetrical nature of the double stranded DNA helix and can occur across cell membranes. The different activities required for the oriented transport of DNA across cell compartments are achieved by three separate modules within the FtsK proteins: a DNA translocation module, an orientation module and an anchoring module. In the second part of this chapter, we review the structural and biochemical properties of these different modules.
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Affiliation(s)
- Gaëlle Demarre
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, Cedex, France,
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24
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Dempwolff F, Wischhusen HM, Specht M, Graumann PL. The deletion of bacterial dynamin and flotillin genes results in pleiotrophic effects on cell division, cell growth and in cell shape maintenance. BMC Microbiol 2012; 12:298. [PMID: 23249255 PMCID: PMC3551649 DOI: 10.1186/1471-2180-12-298] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 12/07/2012] [Indexed: 11/24/2022] Open
Abstract
Background In eukaryotic cells, dynamin and flotillin are involved in processes such as endocytosis and lipid raft formation, respectively. Dynamin is a GTPase that exerts motor-like activity during the pinching off of vesicles, while flotillins are coiled coil rich membrane proteins with no known enzymatic activity. Bacteria also possess orthologs of both classes of proteins, but their function has been unclear. Results We show that deletion of the single dynA or floT genes lead to no phenotype or a mild defect in septum formation in the case of the dynA gene, while dynA floT double mutant cells were highly elongated and irregularly shaped, although the MreB cytoskeleton appeared to be normal. DynA colocalizes with FtsZ, and the dynA deletion strain shows aberrant FtsZ rings in a subpopulation of cells. The mild division defect of the dynA deletion is exacerbated by an additional deletion in ezrA, which affects FtsZ ring formation, and also by the deletion of a late division gene (divIB), indicating that DynA affects several steps in cell division. DynA and mreB deletions generated a synthetic defect in cell shape maintenance, showing that MreB and DynA play non-epistatic functions in cell shape maintenance. TIRF microscopy revealed that FloT forms many dynamic membrane assemblies that frequently colocalize with the division septum. The deletion of dynA did not change the pattern of localization of FloT, and vice versa, showing that the two proteins play non redundant roles in a variety of cellular processes. Expression of dynamin or flotillin T in eukaryotic S2 cells revealed that both proteins assemble at the cell membrane. While FloT formed patch structures, DynA built up tubulated structures extending away from the cells. Conclusions Bacillus subtilis dynamin ortholog DynA plays a role during cell division and in cell shape maintenance. It shows a genetic link with flotillin T, with both proteins playing non-redundant functions at the cell membrane, where they assemble even in the absence of any bacterial cofactor.
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Affiliation(s)
- Felix Dempwolff
- Mikrobiologie, Fachbereich für Biologie, University of Freiburg, Schänzlestraße 1, Freiburg 79104, Germany
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Cabezon E, Lanza VF, Arechaga I. Membrane-associated nanomotors for macromolecular transport. Curr Opin Biotechnol 2011; 23:537-44. [PMID: 22189002 DOI: 10.1016/j.copbio.2011.11.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 11/18/2011] [Accepted: 11/25/2011] [Indexed: 11/19/2022]
Abstract
Nature has endowed cells with powerful nanomotors to accomplish intricate mechanical tasks, such as the macromolecular transport across membranes occurring in cell division, bacterial conjugation, and in a wide variety of secretion systems. These biological motors couple the chemical energy provided by ATP hydrolysis to the mechanical work needed to transport DNA and/or protein effectors. Here, we review what is known about the molecular mechanisms of these membrane-associated machines. Sequence and structural comparison between these ATPases reveal that they share a similar motor domain, suggesting a common evolutionary ancestor. Learning how these machines operate will lead the design of nanotechnology devices with unique applications in medicine and engineering.
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Affiliation(s)
- Elena Cabezon
- Departamento de Biología Molecular, Universidad de Cantabria, and Instituto de Biomedicina y Biotecnología de Cantabria, UC-SODERCAN-CSIC, C. Herrera Oria s/n, 39011 Santander, Spain.
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26
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Ghinet MG, Bordeleau E, Beaudin J, Brzezinski R, Roy S, Burrus V. Uncovering the prevalence and diversity of integrating conjugative elements in actinobacteria. PLoS One 2011; 6:e27846. [PMID: 22114709 PMCID: PMC3218068 DOI: 10.1371/journal.pone.0027846] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 10/26/2011] [Indexed: 12/01/2022] Open
Abstract
Horizontal gene transfer greatly facilitates rapid genetic adaptation of bacteria to shifts in environmental conditions and colonization of new niches by allowing one-step acquisition of novel functions. Conjugation is a major mechanism of horizontal gene transfer mediated by conjugative plasmids and integrating conjugative elements (ICEs). While in most bacterial conjugative systems DNA translocation requires the assembly of a complex type IV secretion system (T4SS), in Actinobacteria a single DNA FtsK/SpoIIIE-like translocation protein is required. To date, the role and diversity of ICEs in Actinobacteria have received little attention. Putative ICEs were searched for in 275 genomes of Actinobacteria using HMM-profiles of proteins involved in ICE maintenance and transfer. These exhaustive analyses revealed 144 putative FtsK/SpoIIIE-type ICEs and 17 putative T4SS-type ICEs. Grouping of the ICEs based on the phylogenetic analyses of maintenance and transfer proteins revealed extensive exchanges between different sub-families of ICEs. 17 ICEs were found in Actinobacteria from the genus Frankia, globally important nitrogen-fixing microorganisms that establish root nodule symbioses with actinorhizal plants. Structural analysis of ICEs from Frankia revealed their unexpected diversity and a vast array of predicted adaptive functions. Frankia ICEs were found to excise by site-specific recombination from their host's chromosome in vitro and in planta suggesting that they are functional mobile elements whether Frankiae live as soil saprophytes or plant endosymbionts. Phylogenetic analyses of proteins involved in ICEs maintenance and transfer suggests that active exchange between ICEs cargo-borne and chromosomal genes took place within the Actinomycetales order. Functionality of Frankia ICEs in vitro as well as in planta lets us anticipate that conjugation and ICEs could allow the development of genetic manipulation tools for this challenging microorganism and for many other Actinobacteria.
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Affiliation(s)
- Mariana Gabriela Ghinet
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Eric Bordeleau
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Julie Beaudin
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Ryszard Brzezinski
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Sébastien Roy
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail: (SR); (VB)
| | - Vincent Burrus
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
- * E-mail: (SR); (VB)
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Kaimer C, Graumann PL. Players between the worlds: multifunctional DNA translocases. Curr Opin Microbiol 2011; 14:719-25. [PMID: 22047950 DOI: 10.1016/j.mib.2011.10.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/04/2011] [Accepted: 10/10/2011] [Indexed: 01/17/2023]
Abstract
DNA translocases play important roles during the bacterial cell cycle and in cell differentiation. Escherichia coli cells contain a multifunctional translocase, FtsK, which is involved in cell division, late steps of chromosome segregation and dimer resolution. In Gram-positive bacteria, the latter two processes are achieved by two translocases, SftA and SpoIIIE. These two translocases operate in a two step fashion, before and after closure of the division septum. DNA translocases have the remarkable ability to translocate DNA in a vectorial manner, orienting themselves according to polar sequences present in bacterial genomes, and perform various additional roles during the cell cycle. DNA translocases genetically interact with Structural Maintenance of Chromosomes (SMC) proteins in a flexible manner in different species, underlining the high versatility of this class of proteins.
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Affiliation(s)
- Christine Kaimer
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720, USA
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28
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Higgins D, Dworkin J. Recent progress in Bacillus subtilis sporulation. FEMS Microbiol Rev 2011; 36:131-48. [PMID: 22091839 DOI: 10.1111/j.1574-6976.2011.00310.x] [Citation(s) in RCA: 314] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 08/25/2011] [Accepted: 09/02/2011] [Indexed: 11/29/2022] Open
Abstract
The Gram-positive bacterium Bacillus subtilis can initiate the process of sporulation under conditions of nutrient limitation. Here, we review some of the last 5 years of work in this area, with a particular focus on the decision to initiate sporulation, DNA translocation, cell-cell communication, protein localization and spore morphogenesis. The progress we describe has implications not only just for the study of sporulation but also for other biological systems where homologs of sporulation-specific proteins are involved in vegetative growth.
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Affiliation(s)
- Douglas Higgins
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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29
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Deghorain M, Pagès C, Meile JC, Stouf M, Capiaux H, Mercier R, Lesterlin C, Hallet B, Cornet F. A defined terminal region of the E. coli chromosome shows late segregation and high FtsK activity. PLoS One 2011; 6:e22164. [PMID: 21799784 PMCID: PMC3140498 DOI: 10.1371/journal.pone.0022164] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 06/16/2011] [Indexed: 11/19/2022] Open
Abstract
Background The FtsK DNA-translocase controls the last steps of chromosome segregation in E. coli. It translocates sister chromosomes using the KOPS DNA motifs to orient its activity, and controls the resolution of dimeric forms of sister chromosomes by XerCD-mediated recombination at the dif site and their decatenation by TopoIV. Methodology We have used XerCD/dif recombination as a genetic trap to probe the interaction of FtsK with loci located in different regions of the chromosome. This assay revealed that the activity of FtsK is restricted to a ∼400 kb terminal region of the chromosome around the natural position of the dif site. Preferential interaction with this region required the tethering of FtsK to the division septum via its N-terminal domain as well as its translocation activity. However, the KOPS-recognition activity of FtsK was not required. Displacement of replication termination outside the FtsK high activity region had no effect on FtsK activity and deletion of a part of this region was not compensated by its extension to neighbouring regions. By observing the fate of fluorescent-tagged loci of the ter region, we found that segregation of the FtsK high activity region is delayed compared to that of its adjacent regions. Significance Our results show that a restricted terminal region of the chromosome is specifically dedicated to the last steps of chromosome segregation and to their coupling with cell division by FtsK.
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Affiliation(s)
- Marie Deghorain
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
- Université Catholique de Louvain, Institut des Sciences de la Vie, Unité de Génétique, Louvain-La-Neuve, Belgium
| | - Carine Pagès
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Jean-Christophe Meile
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Mathieu Stouf
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Hervé Capiaux
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Romain Mercier
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Christian Lesterlin
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Bernard Hallet
- Université Catholique de Louvain, Institut des Sciences de la Vie, Unité de Génétique, Louvain-La-Neuve, Belgium
| | - François Cornet
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
- * E-mail:
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30
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Ayora S, Carrasco B, Cárdenas PP, César CE, Cañas C, Yadav T, Marchisone C, Alonso JC. Double-strand break repair in bacteria: a view from Bacillus subtilis. FEMS Microbiol Rev 2011; 35:1055-81. [PMID: 21517913 DOI: 10.1111/j.1574-6976.2011.00272.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In all living organisms, the response to double-strand breaks (DSBs) is critical for the maintenance of chromosome integrity. Homologous recombination (HR), which utilizes a homologous template to prime DNA synthesis and to restore genetic information lost at the DNA break site, is a complex multistep response. In Bacillus subtilis, this response can be subdivided into five general acts: (1) recognition of the break site(s) and formation of a repair center (RC), which enables cells to commit to HR; (2) end-processing of the broken end(s) by different avenues to generate a 3'-tailed duplex and RecN-mediated DSB 'coordination'; (3) loading of RecA onto single-strand DNA at the RecN-induced RC and concomitant DNA strand exchange; (4) branch migration and resolution, or dissolution, of the recombination intermediates, and replication restart, followed by (5) disassembly of the recombination apparatus formed at the dynamic RC and segregation of sister chromosomes. When HR is impaired or an intact homologous template is not available, error-prone nonhomologous end-joining directly rejoins the two broken ends by ligation. In this review, we examine the functions that are known to contribute to DNA DSB repair in B. subtilis, and compare their properties with those of other bacterial phyla.
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Affiliation(s)
- Silvia Ayora
- Departmento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, Madrid, Spain
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31
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Touzain F, Petit MA, Schbath S, El Karoui M. DNA motifs that sculpt the bacterial chromosome. Nat Rev Microbiol 2011; 9:15-26. [PMID: 21164534 DOI: 10.1038/nrmicro2477] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
During the bacterial cell cycle, the processes of chromosome replication, DNA segregation, DNA repair and cell division are coordinated by precisely defined events. Tremendous progress has been made in recent years in identifying the mechanisms that underlie these processes. A striking feature common to these processes is that non-coding DNA motifs play a central part, thus 'sculpting' the bacterial chromosome. Here, we review the roles of these motifs in the mechanisms that ensure faithful transmission of genetic information to daughter cells. We show how their chromosomal distribution is crucial for their function and how it can be analysed quantitatively. Finally, the potential roles of these motifs in bacterial chromosome evolution are discussed.
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Affiliation(s)
- Fabrice Touzain
- INRA, UMR 1319, Institut Micalis, FR-78352, Jouy-en-Josas, France
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32
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Two DNA translocases synergistically affect chromosome dimer resolution in Bacillus subtilis. J Bacteriol 2011; 193:1334-40. [PMID: 21239579 DOI: 10.1128/jb.00918-10] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus subtilis, chromosome dimers that block complete segregation of sister chromosomes arise in about 15% of exponentially growing cells. Two dedicated recombinases, RipX and CodV, catalyze the resolution of dimers by site-specific recombination at the dif site, which is located close to the terminus region on the chromosome. We show that the two DNA translocases in B. subtilis, SftA and SpoIIIE, synergistically affect dimer resolution, presumably by positioning the dif sites in close proximity, before or after completion of cell division, respectively. Furthermore, we observed that both recombinases, RipX and CodV, assemble on the chromosome at the dif site throughout the cell cycle. The preassembly of recombinases probably ensures that dimer resolution can occur rapidly within a short time window around cell division.
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33
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The putative hydrolase YycJ (WalJ) affects the coordination of cell division with DNA replication in Bacillus subtilis and may play a conserved role in cell wall metabolism. J Bacteriol 2010; 193:896-908. [PMID: 21169496 DOI: 10.1128/jb.00594-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria must accurately replicate and segregate their genetic information to ensure the production of viable daughter cells. The high fidelity of chromosome partitioning is achieved through mechanisms that coordinate cell division with DNA replication. We report that YycJ (WalJ), a predicted member of the metallo-β-lactamase superfamily found in most low-G+C Gram-positive bacteria, contributes to the fidelity of cell division in Bacillus subtilis. B. subtilis ΔwalJ (ΔwalJ(Bsu)) mutants divide over unsegregated chromosomes more frequently than wild-type cells, and this phenotype is exacerbated when DNA replication is inhibited. Two lines of evidence suggest that WalJ(Bsu) and its ortholog in the Gram-positive pathogen Streptococcus pneumoniae, WalJ(Spn) (VicX), play a role in cell wall metabolism: (i) strains of B. subtilis and S. pneumoniae lacking walJ exhibit increased sensitivity to a narrow spectrum of cephalosporin antibiotics, and (ii) reducing the expression of a two-component system that regulates genes involved in cell wall metabolism, WalRK (YycFG), renders walJ essential for growth in B. subtilis, as observed previously with S. pneumoniae. Together, these results suggest that the enzymatic activity of WalJ directly or indirectly affects cell wall metabolism and is required for accurate coordination of cell division with DNA replication.
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34
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Dubarry N, Possoz C, Barre FX. Multiple regions along the Escherichia coli FtsK protein are implicated in cell division. Mol Microbiol 2010; 78:1088-100. [DOI: 10.1111/j.1365-2958.2010.07412.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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35
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Abstract
DNA pumps play important roles in bacteria during cell division and during the transfer of genetic material by conjugation and transformation. The FtsK/SpoIIIE proteins carry out the translocation of double-stranded DNA to ensure complete chromosome segregation during cell division. In contrast, the complex molecular machines that mediate conjugation and genetic transformation drive the transport of single stranded DNA. The transformation machine also processes this internalized DNA and mediates its recombination with the resident chromosome during and after uptake, whereas the conjugation apparatus processes DNA before transfer. This article reviews these three types of DNA pumps, with attention to what is understood of their molecular mechanisms, their energetics and their cellular localizations.
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Affiliation(s)
- Briana Burton
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
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36
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Nolivos S, Pages C, Rousseau P, Le Bourgeois P, Cornet F. Are two better than one? Analysis of an FtsK/Xer recombination system that uses a single recombinase. Nucleic Acids Res 2010. [PMID: 20542912 DOI: 10.1093/nar/gkq507.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Bacteria harbouring circular chromosomes have a Xer site-specific recombination system that resolves chromosome dimers at division. In Escherichia coli, the activity of the XerCD/dif system is controlled and coupled with cell division by the FtsK DNA translocase. Most Xer systems, as XerCD/dif, include two different recombinases. However, some, as the Lactococcus lactis XerS/dif(SL) system, include only one recombinase. We investigated the functional effects of this difference by studying the XerS/dif(SL) system. XerS bound and recombined dif(SL) sites in vitro, both activities displaying asymmetric characteristics. Resolution of chromosome dimers by XerS/dif(SL) required translocation by division septum-borne FtsK. The translocase domain of L. lactis FtsK supported recombination by XerCD/dif, just as E. coli FtsK supports recombination by XerS/dif(SL). Thus, the FtsK-dependent coupling of chromosome segregation with cell division extends to non-rod-shaped bacteria and outside the phylum Proteobacteria. Both the XerCD/dif and XerS/dif(SL) recombination systems require the control activities of the FtsKγ subdomain. However, FtsKγ activates recombination through different mechanisms in these two Xer systems. We show that FtsKγ alone activates XerCD/dif recombination. In contrast, both FtsKγ and the translocation motor are required to activate XerS/dif(SL) recombination. These findings have implications for the mechanisms by which FtsK activates recombination.
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Affiliation(s)
- Sophie Nolivos
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS and Université de Toulouse, Université Paul Sabatier, F-31000 Toulouse, France
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37
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Nolivos S, Pages C, Rousseau P, Le Bourgeois P, Cornet F. Are two better than one? Analysis of an FtsK/Xer recombination system that uses a single recombinase. Nucleic Acids Res 2010; 38:6477-89. [PMID: 20542912 PMCID: PMC2965235 DOI: 10.1093/nar/gkq507] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bacteria harbouring circular chromosomes have a Xer site-specific recombination system that resolves chromosome dimers at division. In Escherichia coli, the activity of the XerCD/dif system is controlled and coupled with cell division by the FtsK DNA translocase. Most Xer systems, as XerCD/dif, include two different recombinases. However, some, as the Lactococcus lactis XerS/dif(SL) system, include only one recombinase. We investigated the functional effects of this difference by studying the XerS/dif(SL) system. XerS bound and recombined dif(SL) sites in vitro, both activities displaying asymmetric characteristics. Resolution of chromosome dimers by XerS/dif(SL) required translocation by division septum-borne FtsK. The translocase domain of L. lactis FtsK supported recombination by XerCD/dif, just as E. coli FtsK supports recombination by XerS/dif(SL). Thus, the FtsK-dependent coupling of chromosome segregation with cell division extends to non-rod-shaped bacteria and outside the phylum Proteobacteria. Both the XerCD/dif and XerS/dif(SL) recombination systems require the control activities of the FtsKγ subdomain. However, FtsKγ activates recombination through different mechanisms in these two Xer systems. We show that FtsKγ alone activates XerCD/dif recombination. In contrast, both FtsKγ and the translocation motor are required to activate XerS/dif(SL) recombination. These findings have implications for the mechanisms by which FtsK activates recombination.
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Affiliation(s)
- Sophie Nolivos
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS and Université de Toulouse, Université Paul Sabatier, F-31000 Toulouse, France
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38
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Contribution of SMC (structural maintenance of chromosomes) and SpoIIIE to chromosome segregation in Staphylococci. J Bacteriol 2010; 192:4067-73. [PMID: 20525833 DOI: 10.1128/jb.00010-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In contrast to rod-shaped bacteria, little is known about chromosomal maintenance and segregation in the spherical Staphylococcus aureus. The analysis of chromosomal segregation in smc (structural maintenance of chromosomes) and spoIIIE single and double mutants unravels differences in the chromosome dynamics in the spherical staphylococcal cells compared to the model in rods.
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39
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Kaimer C, Graumann PL. Bacillus subtilis CinA is a stationary phase-induced protein that localizes to the nucleoid and plays a minor role in competent cells. Arch Microbiol 2010; 192:549-57. [PMID: 20480359 DOI: 10.1007/s00203-010-0583-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 04/20/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
CinA is a conserved bacterial protein that has been reported to play an important role during competence in Streptococcus pneumoniae by recruiting the RecA protein to the cell membrane. Here, we provide information on the homologous CinA in Bacillus subtilis. We found that the synthesis of CinA is upregulated during stationary phase in all cells. The loss of CinA has a mild effect during competence, but it has no influence on the localization of RecA. CinA was observed to be associated with the nucleoid in the cell, and not with the cell membrane, as shown for S. pneumoniae. Purified CinA is a soluble protein, probably forming trimers, like other homologues, which share a domain with CinA that has been reported to be involved in molybdopterine biosynthesis. Our results suggest that CinA plays a nucleoid-associated general role in cells entering stationary phase that is not specific to competence in B. subtilis and possibly in many other bacteria.
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Affiliation(s)
- Christine Kaimer
- Mikrobiologie, Fachbereich für Biologie, Universität Freiburg, Schänzle Strasse 1, 79104 Freiburg, Germany
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40
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Bacillus does the two-step. Nat Rev Microbiol 2010. [DOI: 10.1038/nrmicro2288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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41
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Abstract
The DNA translocase function of Bacillus subtilis SpoIIIE is essential for spore development and is important during vegetative growth for moving trapped chromosomal DNA away from division septa. Two papers in this issue of Molecular Microbiology, from the teams of Peter Graumann and William Burkholder, have characterized a second SpoIIIE/FtsK-like protein in B. subtilis, SftA. This protein lacks any recognizable transmembrane domain possessed by the other characterized members of the family, yet the protein is shown to be associated with the division septum and, like SpoIIIE, is required for clearing DNA from the septum. However, SftA and SpoIIIE act at different stages of septation and together they ensure maximum fidelity in chromosome segregation.
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Affiliation(s)
- Ling Juan Wu
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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Biller SJ, Burkholder WF. The Bacillus subtilis SftA (YtpS) and SpoIIIE DNA translocases play distinct roles in growing cells to ensure faithful chromosome partitioning. Mol Microbiol 2009; 74:790-809. [PMID: 19788545 DOI: 10.1111/j.1365-2958.2009.06893.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In several bacterial species, the faithful completion of chromosome partitioning is known to be promoted by a conserved family of DNA translocases that includes Escherichia coli FtsK and Bacillus subtilis SpoIIIE. FtsK localizes at nascent division sites during every cell cycle and stimulates chromosome decatenation and the resolution of chromosome dimers formed by recA-dependent homologous recombination. In contrast, SpoIIIE localizes at sites where cells have divided and trapped chromosomal DNA in the membrane, which happens during spore development and under some conditions when DNA replication is perturbed. SpoIIIE completes chromosome segregation post-septationally by translocating trapped DNA across the membrane. Unlike E. coli, B. subtilis contains a second uncharacterized FtsK/SpoIIIE-like protein, SftA (formerly YtpS). We report that SftA plays a role similar to FtsK during each cell cycle but cannot substitute for SpoIIIE in rescuing trapped chromosomes. SftA colocalizes with FtsZ at nascent division sites but not with SpoIIIE at sites of chromosome trapping. SftA mutants divide over unsegregated chromosomes more frequently than wild-type unless recA is inactivated, suggesting that SftA, like FtsK, stimulates chromosome dimer resolution. Having two FtsK/SpoIIIE paralogues is not conserved among endospore-forming bacteria, but is highly conserved within several groups of soil- and plant-associated bacteria.
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Affiliation(s)
- Steven J Biller
- Department of Biology, Stanford University, Stanford, CA 94305-5020, USA
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