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Perkins A, Mounange-Badimi MS, Margolin W. Role of the antiparallel double-stranded filament form of FtsA in activating the Escherichia coli divisome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.24.600433. [PMID: 38979378 PMCID: PMC11230281 DOI: 10.1101/2024.06.24.600433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The actin-like FtsA protein is essential for function of the cell division machinery, or divisome, in many bacteria including Escherichia coli. Previous in vitro studies demonstrated that purified wild-type FtsA assembles into closed mini-rings on lipid membranes, but oligomeric variants of FtsA such as FtsAR286W and FtsAG50E can bypass certain divisome defects and form arc and double-stranded (DS) oligomeric states, respectively, which may reflect conversion of an inactive to an active form of FtsA. Yet, it remains unproven which oligomeric forms of FtsA are responsible for assembling and activating the divisome. Here we used an in vivo crosslinking assay for FtsA DS filaments to show that they largely depend on proper divisome assembly and are prevalent at later stages of cell division. We also used a previously reported variant that fails to assemble DS filaments, FtsAM96E R153D, to investigate the roles of FtsA oligomeric states in divisome assembly and activation. We show that FtsAM96E R153D cannot form DS filaments in vivo, fails to replace native FtsA, and confers a dominant negative phenotype, underscoring the importance of the DS filament stage for FtsA function. Surprisingly, however, activation of the divisome through the ftsL* or ftsW* superfission alleles suppressed the dominant negative phenotype and rescued the functionallity of FtsAM96E R153D. Our results suggest that FtsA DS filaments are needed for divisome activation once it is assembled, but they are not essential for divisome assembly or guiding septum synthesis.
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Affiliation(s)
- Abbigale Perkins
- Microbiology and Molecular Genetics, UTHealth McGovern Medical School, 6431 Fannin Street, Houston, TX 77030
| | - Mwidy Sava Mounange-Badimi
- Microbiology and Molecular Genetics, UTHealth McGovern Medical School, 6431 Fannin Street, Houston, TX 77030
| | - William Margolin
- Microbiology and Molecular Genetics, UTHealth McGovern Medical School, 6431 Fannin Street, Houston, TX 77030
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2
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Perez AJ, Xiao J. Stay on track - revelations of bacterial cell wall synthesis enzymes and things that go by single-molecule imaging. Curr Opin Microbiol 2024; 79:102490. [PMID: 38821027 PMCID: PMC11162910 DOI: 10.1016/j.mib.2024.102490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 06/02/2024]
Abstract
In this review, we explore the regulation of septal peptidoglycan (sPG) synthesis in bacterial cell division, a critical process for cell viability and proper morphology. Recent single-molecule imaging studies have revealed the processive movement of the FtsW:bPBP synthase complex along the septum, shedding light on the spatiotemporal dynamics of sPG synthases and their regulators. In diderm bacteria (E. coli and C. crescentus), the movement occurs at two distinct speeds, reflecting active synthesis or inactivity driven by FtsZ-treadmilling. In monoderm bacteria (B. subtilis, S. pneumoniae, and S. aureus), however, these enzymes exhibit only the active sPG-track-coupled processive movement. By comparing the dynamics of sPG synthases in these organisms and that of class-A penicillin-binding proteins in vivo and in vitro, we propose a unifying model for septal cell wall synthesis regulation across species, highlighting the roles of the sPG- and Z-tracks in orchestrating a robust bacterial cell wall constriction process.
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Affiliation(s)
- Amilcar J Perez
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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3
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Whitley KD, Grimshaw J, Roberts DM, Karinou E, Stansfeld PJ, Holden S. Peptidoglycan synthesis drives a single population of septal cell wall synthases during division in Bacillus subtilis. Nat Microbiol 2024; 9:1064-1074. [PMID: 38480901 PMCID: PMC10994842 DOI: 10.1038/s41564-024-01650-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/23/2024] [Indexed: 04/06/2024]
Abstract
Bacterial cell division requires septal peptidoglycan (sPG) synthesis by the divisome complex. Treadmilling of the essential tubulin homologue FtsZ has been implicated in septal constriction, though its precise role remains unclear. Here we used live-cell single-molecule imaging of the divisome transpeptidase PBP2B to investigate sPG synthesis dynamics in Bacillus subtilis. In contrast to previous models, we observed a single population of processively moving PBP2B molecules whose motion is driven by peptidoglycan synthesis and is not associated with FtsZ treadmilling. However, despite the asynchronous motions of PBP2B and FtsZ, a partial dependence of PBP2B processivity on FtsZ treadmilling was observed. Additionally, through single-molecule counting experiments we provide evidence that the divisome synthesis complex is multimeric. Our results support a model for B. subtilis division where a multimeric synthesis complex follows a single track dependent on sPG synthesis whose activity and dynamics are asynchronous with FtsZ treadmilling.
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Affiliation(s)
- Kevin D Whitley
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - James Grimshaw
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - David M Roberts
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Eleni Karinou
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Phillip J Stansfeld
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Séamus Holden
- School of Life Sciences, University of Warwick, Coventry, UK.
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4
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Radler P, Loose M. A dynamic duo: Understanding the roles of FtsZ and FtsA for Escherichia coli cell division through in vitro approaches. Eur J Cell Biol 2024; 103:151380. [PMID: 38218128 DOI: 10.1016/j.ejcb.2023.151380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/15/2024] Open
Abstract
Bacteria divide by binary fission. The protein machine responsible for this process is the divisome, a transient assembly of more than 30 proteins in and on the surface of the cytoplasmic membrane. Together, they constrict the cell envelope and remodel the peptidoglycan layer to eventually split the cell into two. For Escherichia coli, most molecular players involved in this process have probably been identified, but obtaining the quantitative information needed for a mechanistic understanding can often not be achieved from experiments in vivo alone. Since the discovery of the Z-ring more than 30 years ago, in vitro reconstitution experiments have been crucial to shed light on molecular processes normally hidden in the complex environment of the living cell. In this review, we summarize how rebuilding the divisome from purified components - or at least parts of it - have been instrumental to obtain the detailed mechanistic understanding of the bacterial cell division machinery that we have today.
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Affiliation(s)
- Philipp Radler
- Institute for Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria; University of Vienna, Djerassiplatz 1, 1030 Wien, Austria.
| | - Martin Loose
- Institute for Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria.
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5
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Cameron TA, Margolin W. Insights into the assembly and regulation of the bacterial divisome. Nat Rev Microbiol 2024; 22:33-45. [PMID: 37524757 PMCID: PMC11102604 DOI: 10.1038/s41579-023-00942-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2023] [Indexed: 08/02/2023]
Abstract
The ability to split one cell into two is fundamental to all life, and many bacteria can accomplish this feat several times per hour with high accuracy. Most bacteria call on an ancient homologue of tubulin, called FtsZ, to localize and organize the cell division machinery, the divisome, into a ring-like structure at the cell midpoint. The divisome includes numerous other proteins, often including an actin homologue (FtsA), that interact with each other at the cytoplasmic membrane. Once assembled, the protein complexes that comprise the dynamic divisome coordinate membrane constriction with synthesis of a division septum, but only after overcoming checkpoints mediated by specialized protein-protein interactions. In this Review, we summarize the most recent evidence showing how the divisome proteins of Escherichia coli assemble at the cell midpoint, interact with each other and regulate activation of septum synthesis. We also briefly discuss the potential of divisome proteins as novel antibiotic targets.
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Affiliation(s)
- Todd A Cameron
- Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, TX, USA
| | - William Margolin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, Houston, TX, USA.
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Umeda S, Sujino T, Miyamoto K, Yoshimatsu Y, Harada Y, Nishiyama K, Aoto Y, Adachi K, Hayashi N, Amafuji K, Moritoki N, Shibata S, Sasaki N, Mita M, Tanemoto S, Ono K, Mikami Y, Sasabe J, Takabayashi K, Hosoe N, Suzuki T, Sato T, Atarashi K, Teratani T, Ogata H, Nakamoto N, Shiomi D, Ashida H, Kanai T. D-amino Acids Ameliorate Experimental Colitis and Cholangitis by Inhibiting Growth of Proteobacteria: Potential Therapeutic Role in Inflammatory Bowel Disease. Cell Mol Gastroenterol Hepatol 2023; 16:1011-1031. [PMID: 37567385 PMCID: PMC10632532 DOI: 10.1016/j.jcmgh.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023]
Abstract
BACKGROUND & AIMS D-amino acids, the chiral counterparts of protein L-amino acids, were primarily produced and utilized by microbes, including those in the human gut. However, little was known about how orally administered or microbe-derived D-amino acids affected the gut microbial community or gut disease progression. METHODS The ratio of D- to L-amino acids was analyzed in feces and blood from patients with ulcerative colitis (UC) and healthy controls. Also, composition of microbe was analyzed from patients with UC. Mice were treated with D-amino acid in dextran sulfate sodium colitis model and liver cholangitis model. RESULTS The ratio of D- to L-amino acids was lower in the feces of patients with UC than that of healthy controls. Supplementation of D-amino acids ameliorated UC-related experimental colitis and liver cholangitis by inhibiting growth of Proteobacteria. Addition of D-alanine, a major building block for bacterial cell wall formation, to culture medium inhibited expression of the ftsZ gene required for cell fission in the Proteobacteria Escherichia coli and Klebsiella pneumoniae, thereby inhibiting growth. Overexpression of ftsZ restored growth of E. coli even when D-alanine was present. We found that D-alanine not only inhibited invasion of pathological K. pneumoniae into the host via pore formation in intestinal epithelial cells but also inhibited growth of E. coli and generation of antibiotic-resistant strains. CONCLUSIONS D-amino acids might have potential for use in novel therapeutic approaches targeting Proteobacteria-associated dysbiosis and antibiotic-resistant bacterial diseases by means of their effects on the intestinal microbiota community.
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Affiliation(s)
- Satoko Umeda
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Tomohisa Sujino
- Center for Diagnostic and Therapeutic Endoscopy, Keio University School of Medicine, Tokyo, Japan.
| | - Kentaro Miyamoto
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan; Miyarisan Pharmaceutical Co, Ltd., Tokyo, Japan
| | - Yusuke Yoshimatsu
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Yosuke Harada
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Keita Nishiyama
- Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan; JSR-Keio University Medical and Chemical Innovation Center (JKiC), Keio University School of Medicine, Tokyo, Japan
| | - Yoshimasa Aoto
- JSR-Keio University Medical and Chemical Innovation Center (JKiC), JSR Corp, Tokyo, Japan
| | - Keika Adachi
- JSR-Keio University Medical and Chemical Innovation Center (JKiC), JSR Corp, Tokyo, Japan
| | - Naoki Hayashi
- JSR-Keio University Medical and Chemical Innovation Center (JKiC), JSR Corp, Tokyo, Japan
| | - Kimiko Amafuji
- JSR-Keio University Medical and Chemical Innovation Center (JKiC), JSR Corp, Tokyo, Japan
| | - Nobuko Moritoki
- Electron Microscope Laboratory, Keio University School of Medicine, Tokyo, Japan
| | - Shinsuke Shibata
- Electron Microscope Laboratory, Keio University School of Medicine, Tokyo, Japan
| | - Nobuo Sasaki
- Institute of Molecular and Cellular Regulation, Gunma University, Maebashi City, Japan
| | | | - Shun Tanemoto
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Keiko Ono
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Yohei Mikami
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Jumpei Sasabe
- Department of Pharmacology, School of Medicine, Keio University, Tokyo, Japan
| | - Kaoru Takabayashi
- Center for Diagnostic and Therapeutic Endoscopy, Keio University School of Medicine, Tokyo, Japan
| | - Naoki Hosoe
- Center for Diagnostic and Therapeutic Endoscopy, Keio University School of Medicine, Tokyo, Japan
| | - Toshihiko Suzuki
- Department of Bacterial Infection and Host Response, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Toshiro Sato
- Department of Organoid Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Koji Atarashi
- Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan
| | - Toshiaki Teratani
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Haruhiko Ogata
- Center for Diagnostic and Therapeutic Endoscopy, Keio University School of Medicine, Tokyo, Japan
| | - Nobuhiro Nakamoto
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Daisuke Shiomi
- Department of Life Science, College of Science, Rikkyo University, Tokyo, Japan
| | - Hiroshi Ashida
- Department of Bacterial Infection and Host Response, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Medical Mycology Research Center, Chiba University, Chiba, Japan
| | - Takanori Kanai
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan; AMED-CREST, Tokyo, Japan.
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7
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Leonard TA, Loose M, Martens S. The membrane surface as a platform that organizes cellular and biochemical processes. Dev Cell 2023; 58:1315-1332. [PMID: 37419118 DOI: 10.1016/j.devcel.2023.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/22/2023] [Accepted: 06/08/2023] [Indexed: 07/09/2023]
Abstract
Membranes are essential for life. They act as semi-permeable boundaries that define cells and organelles. In addition, their surfaces actively participate in biochemical reaction networks, where they confine proteins, align reaction partners, and directly control enzymatic activities. Membrane-localized reactions shape cellular membranes, define the identity of organelles, compartmentalize biochemical processes, and can even be the source of signaling gradients that originate at the plasma membrane and reach into the cytoplasm and nucleus. The membrane surface is, therefore, an essential platform upon which myriad cellular processes are scaffolded. In this review, we summarize our current understanding of the biophysics and biochemistry of membrane-localized reactions with particular focus on insights derived from reconstituted and cellular systems. We discuss how the interplay of cellular factors results in their self-organization, condensation, assembly, and activity, and the emergent properties derived from them.
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Affiliation(s)
- Thomas A Leonard
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9, 1030, Vienna, Austria; Medical University of Vienna, Center for Medical Biochemistry, Dr. Bohr-Gasse 9, 1030, Vienna, Austria.
| | - Martin Loose
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
| | - Sascha Martens
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9, 1030, Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr. Bohr-Gasse 9, 1030, Vienna, Austria.
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8
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Morrison JJ, Ferreira CN, Siler EM, Nelson K, Trebino CE, Piraino B, Camberg JL. Nucleotide-dependent activities of FtsA regulate the early establishment of a functional divisome during the Escherichia coli cell cycle. Front Microbiol 2023; 14:1171376. [PMID: 37250038 PMCID: PMC10213515 DOI: 10.3389/fmicb.2023.1171376] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
During cell division in Escherichia coli, the highly conserved tubulin homolog FtsZ polymerizes and assembles into a ring-like structure, called the Z-ring, at the site of septation. For recruitment to the membrane surface, FtsZ polymers directly interact with membrane-associated proteins, predominantly FtsA in E. coli. FtsA shares structural homology with actin and, like actin, hydrolyzes ATP. Yeast actin detects nucleotide occupancy through a sensor region adjacent to the nucleotide binding site and adopts distinct conformations in monomeric and filamentous actin. Bacterial actin homologs also display considerable conformational flexibility across different nucleotide-bound states and polymerize. Here, we show that several amino acid residues proximal to the nucleotide binding site in FtsA are critical for function in vitro and in vivo. Each of these residues are important for ATP hydrolysis, phospholipid (PL) binding, ATP-dependent vesicle remodeling, and recruitment to the divisome in vivo, to varying degrees. Notably, we observed that Ser 84 and Glu 14 are essential for ATP-dependent vesicle remodeling and magnesium-dependent membrane release of FtsA from vesicles in vitro, and these defects likely underlie the loss of function by FtsA(E14R) and FtsA(S84L) in vivo. Finally, we demonstrate that FtsA(A188V), which is associated with temperature-sensitive growth in vivo, is defective for rapid ATP hydrolysis and ATP-dependent remodeling of PL vesicles in vitro. Together, our results show that loss of nucleotide-dependent activities by FtsA, such as ATP hydrolysis, membrane binding and release, and, most importantly, ATP-dependent PL remodeling, lead to failed Z-ring assembly and division defects in cells.
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9
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Puls JS, Brajtenbach D, Schneider T, Kubitscheck U, Grein F. Inhibition of peptidoglycan synthesis is sufficient for total arrest of staphylococcal cell division. SCIENCE ADVANCES 2023; 9:eade9023. [PMID: 36947615 PMCID: PMC10032595 DOI: 10.1126/sciadv.ade9023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Bacterial cell wall biosynthesis is the target of many important antibiotics. Its spatiotemporal organization is closely coordinated with cell division. However, the role of peptidoglycan synthesis within cell division is not fully understood. Even less is known about the impact of antibiotics on the coordination of these two essential processes. Visualizing the essential cell division protein FtsZ and other key proteins in Staphylococcus aureus, we show that antibiotics targeting peptidoglycan synthesis arrest cell division within minutes of treatment. The glycopeptides vancomycin and telavancin completely inhibit septum constriction in all phases of cell division. The beta-lactam oxacillin stops division progress by preventing recruitment of the major peptidoglycan synthase PBP2 to the septum, revealing PBP2 as crucial for septum closure. Our work identifies cell division as key cellular target of these antibiotics and provides evidence that peptidoglycan synthesis is the essential driving force of septum constriction throughout cell division of S. aureus.
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Affiliation(s)
- Jan-Samuel Puls
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Meckenheimer Allee 168, 53115 Bonn, Germany
| | - Dominik Brajtenbach
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Meckenheimer Allee 168, 53115 Bonn, Germany
| | - Ulrich Kubitscheck
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Fabian Grein
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Meckenheimer Allee 168, 53115 Bonn, Germany
- German Center for Infection Research (DZIF), Partner site Bonn-Cologne, 53115 Bonn, Germany
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10
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Godino E, Danelon C. Gene-Directed FtsZ Ring Assembly Generates Constricted Liposomes with Stable Membrane Necks. Adv Biol (Weinh) 2023; 7:e2200172. [PMID: 36593513 DOI: 10.1002/adbi.202200172] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/15/2022] [Indexed: 01/04/2023]
Abstract
Mimicking bacterial cell division in well-defined cell-free systems has the potential to elucidate the minimal set of proteins required for cytoskeletal formation, membrane constriction, and final abscission. Membrane-anchored FtsZ polymers are often regarded as a sufficient system to realize this chain of events. By using purified FtsZ and its membrane-binding protein FtsA or the gain-of-function mutant FtsA* expressed in PURE (Protein synthesis Using Reconstituted Elements) from a DNA template, it is shown in this study that cytoskeletal structures are formed, and yield constricted liposomes exhibiting various morphologies. However, the resulting buds remain attached to the parental liposome by a narrow membrane neck. No division events can be monitored even after long-time tracking by fluorescence microscopy, nor when the osmolarity of the external solution is increased. The results provide evidence that reconstituted FtsA-FtsZ proto-rings coating the membrane necks are too stable to enable abscission. The prospect of combining a DNA-encoded FtsZ system with assisting mechanisms to achieve synthetic cell division is discussed.
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Affiliation(s)
- Elisa Godino
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629HZ, The Netherlands
| | - Christophe Danelon
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629HZ, The Netherlands
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11
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Construction and Characterization of Functional FtsA Sandwich Fusions for Studies of FtsA Localization and Dynamics during Escherichia coli Cell Division. J Bacteriol 2023; 205:e0037322. [PMID: 36622232 PMCID: PMC9879108 DOI: 10.1128/jb.00373-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
FtsA, a homolog of actin, is essential for cell division of Escherichia coli and is widely conserved among many bacteria. FtsA helps to tether polymers of the bacterial tubulin homolog FtsZ to the cytoplasmic membrane as part of the cytokinetic Z ring. GFP fusions to FtsA have illuminated FtsA's localization in live E. coli, but these fusions have not been fully functional and required the presence of the native FtsA. Here, we characterize "sandwich" fusions of E. coli FtsA to either mCherry or msfGFP that are functional for cell division and exhibit fluorescent rings at midcell that persist throughout constriction until cell separation. FtsA within the Z ring moved circumferentially like FtsZ, and FtsA outside the rings formed highly dynamic patches at the membrane. Notably, both FtsA-mCherrysw and FtsA-msfGFPsw acted as mild hypermorphs, as they were not toxic when overproduced, bypassed the essential cell division protein ZipA, and suppressed several thermosensitive fts alleles, although not as effectively as the prototypical hypermorph FtsA*. Overall, our results indicate that fluorescent FtsA sandwich fusions can be used as the sole FtsA in E. coli and thus should shed new light on FtsA dynamics during the cell division cycle in this model system. IMPORTANCE FtsA is a key conserved cell division protein, and E. coli is the most well studied model system for bacterial cell division. One obstacle to full understanding of this process is the lack of a fully functional fluorescent reporter for FtsA in vivo. Here, we describe a fluorescent fusion to E. coli FtsA that promotes efficient cell division in the absence of the native FtsA and can be used to monitor FtsA dynamics during cell division.
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12
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McCoy KM, Fritzsching KJ, McDermott AE. GTP-Bound Escherichia coli FtsZ Filaments Are Composed of Tense Monomers: a Dynamic Nuclear Polarization-Nuclear Magnetic Resonance Study Using Interface Detection. mBio 2022; 13:e0235822. [PMID: 36214571 PMCID: PMC9765660 DOI: 10.1128/mbio.02358-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 09/08/2022] [Indexed: 11/20/2022] Open
Abstract
FtsZ filaments are the major structural component of the bacterial Z ring and are drivers of bacterial division. Crystal structures for FtsZ from some Gram-positive bacteria in the presence of GTP analogs suggest the possibility of a high-energy, "tense" conformation. It remains important to elucidate whether this tense form is the dominant form in filaments. Using dynamic nuclear polarization (DNP) solid-state nuclear magnetic resonance (NMR) and differential isotopic labeling, we directly detected residues located at the intermonomer interface of GTP-bound wild-type (WT) Escherichia coli FtsZ filaments. We combined chemical shift prediction, homology modeling, and heteronuclear dipolar recoupling techniques to characterize the E. coli FtsZ filament interface and demonstrated that the monomers in active filaments assume a tense conformation. IMPORTANCE Bacterial replication is dependent on the cytoskeletal protein FtsZ, which forms filaments that scaffold and recruit other essential division proteins. While the FtsZ monomer is well studied across organisms, many questions remain about how the filaments form and function. Recently, a second monomer form was identified in Staphylococcus aureus that has far-reaching implications for FtsZ structure and function. However, to date, this form has not been directly observed outside S. aureus. In this study, we used solid-state NMR and dynamic nuclear polarization (DNP) to directly study the filaments of E. coli FtsZ to demonstrate that E. coli FtsZ filaments are primarily composed of this second, "tense" form of the monomer. This work is the first time GTP-bound, wild-type FtsZ filaments have been studied directly at atomic resolution and is an important step forward for the study of FtsZ filaments.
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Affiliation(s)
- Kelsey M. McCoy
- Department of Chemistry, Columbia University, New York, New York, USA
| | | | - Ann E. McDermott
- Department of Chemistry, Columbia University, New York, New York, USA
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13
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Nierhaus T, McLaughlin SH, Bürmann F, Kureisaite-Ciziene D, Maslen SL, Skehel JM, Yu CWH, Freund SMV, Funke LFH, Chin JW, Löwe J. Bacterial divisome protein FtsA forms curved antiparallel double filaments when binding to FtsN. Nat Microbiol 2022; 7:1686-1701. [PMID: 36123441 PMCID: PMC7613929 DOI: 10.1038/s41564-022-01206-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 07/19/2022] [Indexed: 11/08/2022]
Abstract
During bacterial cell division, filaments of tubulin-like FtsZ form the Z-ring, which is the cytoplasmic scaffold for divisome assembly. In Escherichia coli, the actin homologue FtsA anchors the Z-ring to the membrane and recruits divisome components, including bitopic FtsN. FtsN regulates the periplasmic peptidoglycan synthase FtsWI. To characterize how FtsA regulates FtsN, we applied electron microscopy to show that E. coli FtsA forms antiparallel double filaments on lipid monolayers when bound to the cytoplasmic tail of FtsN. Using X-ray crystallography, we demonstrate that Vibrio maritimus FtsA crystallizes as an equivalent double filament. We identified an FtsA-FtsN interaction site in the IA-IC interdomain cleft of FtsA using X-ray crystallography and confirmed that FtsA forms double filaments in vivo by site-specific cysteine cross-linking. FtsA-FtsN double filaments reconstituted in or on liposomes prefer negative Gaussian curvature, like those of MreB, the actin-like protein of the elongasome. We propose that curved antiparallel FtsA double filaments together with treadmilling FtsZ filaments organize septal peptidoglycan synthesis in the division plane.
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Affiliation(s)
- Tim Nierhaus
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | | | - Sarah L Maslen
- MRC Laboratory of Molecular Biology, Cambridge, UK
- The Francis Crick Institute, London, UK
| | - J Mark Skehel
- MRC Laboratory of Molecular Biology, Cambridge, UK
- The Francis Crick Institute, London, UK
| | - Conny W H Yu
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | - Jason W Chin
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Cambridge, UK.
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14
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Lyu Z, Yahashiri A, Yang X, McCausland JW, Kaus GM, McQuillen R, Weiss DS, Xiao J. FtsN maintains active septal cell wall synthesis by forming a processive complex with the septum-specific peptidoglycan synthases in E. coli. Nat Commun 2022; 13:5751. [PMID: 36180460 PMCID: PMC9525312 DOI: 10.1038/s41467-022-33404-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 09/16/2022] [Indexed: 01/06/2023] Open
Abstract
FtsN plays an essential role in promoting the inward synthesis of septal peptidoglycan (sPG) by the FtsWI complex during bacterial cell division. How it achieves this role is unclear. Here we use single-molecule tracking to investigate FtsN's dynamics during sPG synthesis in E. coli. We show that septal FtsN molecules move processively at ~9 nm s-1, the same as FtsWI molecules engaged in sPG synthesis (termed sPG-track), but much slower than the ~30 nm s-1 speed of inactive FtsWI molecules coupled to FtsZ's treadmilling dynamics (termed FtsZ-track). Importantly, processive movement of FtsN is exclusively coupled to sPG synthesis and is required to maintain active sPG synthesis by FtsWI. Our findings indicate that FtsN is part of the FtsWI sPG synthesis complex, and that while FtsN is often described as a "trigger" for the initiation for cell wall constriction, it must remain part of the processive FtsWI complex to maintain sPG synthesis activity.
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Affiliation(s)
- Zhixin Lyu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Atsushi Yahashiri
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
- The Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Joshua W McCausland
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Gabriela M Kaus
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Ryan McQuillen
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - David S Weiss
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
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15
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Radler P, Baranova N, Caldas P, Sommer C, López-Pelegrín M, Michalik D, Loose M. In vitro reconstitution of Escherichia coli divisome activation. Nat Commun 2022; 13:2635. [PMID: 35550516 PMCID: PMC9098913 DOI: 10.1038/s41467-022-30301-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 04/25/2022] [Indexed: 01/02/2023] Open
Abstract
The actin-homologue FtsA is essential for E. coli cell division, as it links FtsZ filaments in the Z-ring to transmembrane proteins. FtsA is thought to initiate cell constriction by switching from an inactive polymeric to an active monomeric conformation, which recruits downstream proteins and stabilizes the Z-ring. However, direct biochemical evidence for this mechanism is missing. Here, we use reconstitution experiments and quantitative fluorescence microscopy to study divisome activation in vitro. By comparing wild-type FtsA with FtsA R286W, we find that this hyperactive mutant outperforms FtsA WT in replicating FtsZ treadmilling dynamics, FtsZ filament stabilization and recruitment of FtsN. We could attribute these differences to a faster exchange and denser packing of FtsA R286W below FtsZ filaments. Using FRET microscopy, we also find that FtsN binding promotes FtsA self-interaction. We propose that in the active divisome FtsA and FtsN exist as a dynamic copolymer that follows treadmilling filaments of FtsZ. In E. coli, FtsA and FtsZ control the place and time of cell division. Here, the authors use in vitro experiments to show how FtsA can follow FtsZ treadmilling and that downstream proteins form dynamic copolymers with FtsA to initiate division.
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Affiliation(s)
- Philipp Radler
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Natalia Baranova
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria.,University of Vienna, Department of Pharmaceutical Sciences, Vienna, Austria
| | - Paulo Caldas
- UCIBIO-Applied Molecular Biosciences Unit, Department of Life Sciences, NOVA School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal
| | - Christoph Sommer
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Mar López-Pelegrín
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - David Michalik
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Martin Loose
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
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16
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Perez AJ, Villicana JB, Tsui HCT, Danforth ML, Benedet M, Massidda O, Winkler ME. FtsZ-Ring Regulation and Cell Division Are Mediated by Essential EzrA and Accessory Proteins ZapA and ZapJ in Streptococcus pneumoniae. Front Microbiol 2021; 12:780864. [PMID: 34938281 PMCID: PMC8687745 DOI: 10.3389/fmicb.2021.780864] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 10/22/2021] [Indexed: 12/02/2022] Open
Abstract
The bacterial FtsZ-ring initiates division by recruiting a large repertoire of proteins (the divisome; Z-ring) needed for septation and separation of cells. Although FtsZ is essential and its role as the main orchestrator of cell division is conserved in most eubacteria, the regulators of Z-ring presence and positioning are not universal. This study characterizes factors that regulate divisome presence and placement in the ovoid-shaped pathogen, Streptococcus pneumoniae (Spn), focusing on FtsZ, EzrA, SepF, ZapA, and ZapJ, which is reported here as a partner of ZapA. Epi-fluorescence microscopy (EFm) and high-resolution microscopy experiments showed that FtsZ and EzrA co-localize during the entire Spn cell cycle, whereas ZapA and ZapJ are late-arriving divisome proteins. Depletion and conditional mutants demonstrate that EzrA is essential in Spn and required for normal cell growth, size, shape homeostasis, and chromosome segregation. Moreover, EzrA(Spn) is required for midcell placement of FtsZ-rings and PG synthesis. Notably, overexpression of EzrA leads to the appearance of extra Z-rings in Spn. Together, these observations support a role for EzrA as a positive regulator of FtsZ-ring formation in Spn. Conversely, FtsZ is required for EzrA recruitment to equatorial rings and for the organization of PG synthesis. In contrast to EzrA depletion, which causes a bacteriostatic phenotype in Spn, depletion of FtsZ results in enlarged spherical cells that are subject to LytA-dependent autolysis. Co-immunoprecipitation and bacterial two-hybrid assays show that EzrA(Spn) is in complexes with FtsZ, Z-ring regulators (FtsA, SepF, ZapA, MapZ), division proteins (FtsK, StkP), and proteins that mediate peptidoglycan synthesis (GpsB, aPBP1a), consistent with a role for EzrA at the interface of cell division and PG synthesis. In contrast to the essentiality of FtsZ and EzrA, ZapA and SepF have accessory roles in regulating pneumococcal physiology. We further show that ZapA interacts with a non-ZapB homolog, named here as ZapJ, which is conserved in Streptococcus species. The absence of the accessory proteins, ZapA, ZapJ, and SepF, exacerbates growth defects when EzrA is depleted or MapZ is deleted. Taken together, these results provide new information about the spatially and temporally distinct proteins that regulate FtsZ-ring organization and cell division in Spn.
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Affiliation(s)
- Amilcar J Perez
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Jesus Bazan Villicana
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Ho-Ching T Tsui
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Madeline L Danforth
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Mattia Benedet
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Orietta Massidda
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
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17
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Levin PA, Janakiraman A. Localization, Assembly, and Activation of the Escherichia coli Cell Division Machinery. EcoSal Plus 2021; 9:eESP00222021. [PMID: 34910577 PMCID: PMC8919703 DOI: 10.1128/ecosalplus.esp-0022-2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/14/2021] [Indexed: 01/01/2023]
Abstract
Decades of research, much of it in Escherichia coli, have yielded a wealth of insight into bacterial cell division. Here, we provide an overview of the E. coli division machinery with an emphasis on recent findings. We begin with a short historical perspective into the discovery of FtsZ, the tubulin homolog that is essential for division in bacteria and archaea. We then discuss assembly of the divisome, an FtsZ-dependent multiprotein platform, at the midcell septal site. Not simply a scaffold, the dynamic properties of polymeric FtsZ ensure the efficient and uniform synthesis of septal peptidoglycan. Next, we describe the remodeling of the cell wall, invagination of the cell envelope, and disassembly of the division apparatus culminating in scission of the mother cell into two daughter cells. We conclude this review by highlighting some of the open questions in the cell division field, emphasizing that much remains to be discovered, even in an organism as extensively studied as E. coli.
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Affiliation(s)
- Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Center for Science & Engineering of Living Systems (CSELS), McKelvey School of Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Anuradha Janakiraman
- Department of Biology, The City College of New York, New York, New York, USA
- Programs in Biology and Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA
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18
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Di Somma A, Canè C, Moretta A, Duilio A. Interaction of Temporin-L Analogues with the E. coli FtsZ Protein. Antibiotics (Basel) 2021; 10:antibiotics10060704. [PMID: 34208230 PMCID: PMC8230800 DOI: 10.3390/antibiotics10060704] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 11/16/2022] Open
Abstract
The research of new therapeutic agents to fight bacterial infections has recently focused on the investigation of antimicrobial peptides (AMPs), the most common weapon that all organisms produce to prevent invasion by external pathogens. Among AMPs, the amphibian Temporins constitute a well-known family with high antibacterial properties against Gram-positive and Gram-negative bacteria. In particular, Temporin-L was shown to affect bacterial cell division by inhibiting FtsZ, a tubulin-like protein involved in the crucial step of Z-ring formation at the beginning of the division process. As FtsZ represents a leading target for new antibacterial compounds, in this paper we investigated in detail the interaction of Temporin L with Escherichia coli FtsZ and designed two TL analogues in an attempt to increase peptide-protein interactions and to better understand the structural determinants leading to FtsZ inhibition. The results demonstrated that the TL analogues improved their binding to FtsZ, originating stable protein-peptide complexes. Functional studies showed that both peptides were endowed with a high capability of inhibiting both the enzymatic and polymerization activities of the protein. Moreover, the TL analogues were able to inhibit bacterial growth at low micromolar concentrations. These observations may open up the way to the development of novel peptide or peptidomimetic drugs tailored to bind FtsZ, hampering a crucial process of bacterial life that might be proposed for future pharmaceutical applications.
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Affiliation(s)
- Angela Di Somma
- Department of Chemical Sciences, Università Federico II di Napoli, 80126 Napoli, Italy; (A.D.S.); (C.C.)
| | - Carolina Canè
- Department of Chemical Sciences, Università Federico II di Napoli, 80126 Napoli, Italy; (A.D.S.); (C.C.)
| | - Antonio Moretta
- Departiment of Science, Università degli Studi della Basilicata, 85100 Potenza, Italy;
| | - Angela Duilio
- Department of Chemical Sciences, Università Federico II di Napoli, 80126 Napoli, Italy; (A.D.S.); (C.C.)
- Correspondence:
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19
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FtsZ treadmilling is essential for Z-ring condensation and septal constriction initiation in Bacillus subtilis cell division. Nat Commun 2021; 12:2448. [PMID: 33907196 PMCID: PMC8079713 DOI: 10.1038/s41467-021-22526-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 03/16/2021] [Indexed: 12/16/2022] Open
Abstract
Despite the central role of division in bacterial physiology, how division proteins work together as a nanoscale machine to divide the cell remains poorly understood. Cell division by cell wall synthesis proteins is guided by the cytoskeleton protein FtsZ, which assembles at mid-cell as a dense Z-ring formed of treadmilling filaments. However, although FtsZ treadmilling is essential for cell division, the function of FtsZ treadmilling remains unclear. Here, we systematically resolve the function of FtsZ treadmilling across each stage of division in the Gram-positive model organism Bacillus subtilis using a combination of nanofabrication, advanced microscopy, and microfluidics to measure the division-protein dynamics in live cells with ultrahigh sensitivity. We find that FtsZ treadmilling has two essential functions: mediating condensation of diffuse FtsZ filaments into a dense Z-ring, and initiating constriction by guiding septal cell wall synthesis. After constriction initiation, FtsZ treadmilling has a dispensable function in accelerating septal constriction rate. Our results show that FtsZ treadmilling is critical for assembling and initiating the bacterial cell division machine. Bacterial cell division by cell wall synthesis proteins is guided by treadmilling filaments of the cytoskeleton protein FtsZ. Here authors use nanofabrication, advanced microscopy, and microfluidics to resolve the function of FtsZ treadmilling in the Gram-positive model organism Bacillus subtilis.
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20
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Robles-Ramos MÁ, Zorrilla S, Alfonso C, Margolin W, Rivas G, Monterroso B. Assembly of bacterial cell division protein FtsZ into dynamic biomolecular condensates. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118986. [PMID: 33581219 PMCID: PMC8529516 DOI: 10.1016/j.bbamcr.2021.118986] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 11/30/2022]
Abstract
Biomolecular condensation through phase separation may be a novel mechanism to regulate bacterial processes, including cell division. Previous work revealed that FtsZ, a protein essential for cytokinesis in most bacteria, forms biomolecular condensates with SlmA, a protein that protects the chromosome from damage inflicted by the division machinery in Escherichia coli. The absence of condensates composed solely of FtsZ under the conditions used in that study suggested this mechanism was restricted to nucleoid occlusion by SlmA or to bacteria containing this protein. Here we report that FtsZ alone, under physiologically relevant conditions, can demix into condensates in bulk and when encapsulated in synthetic cell-like systems generated by microfluidics. Condensate assembly depends on FtsZ being in the GDP-bound state and on conditions mimicking the crowded environment of the cytoplasm that promote its oligomerization. Condensates are dynamic and reversibly convert into filaments upon GTP addition. Notably, FtsZ lacking its C-terminal disordered region, a structural element likely to favor biomolecular condensation, also forms condensates, albeit less efficiently. The inherent tendency of FtsZ to form condensates susceptible to modulation by physiological factors, including binding partners, suggests that such mechanisms may play a more general role in bacterial division than initially envisioned.
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Affiliation(s)
- Miguel Ángel Robles-Ramos
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Silvia Zorrilla
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - William Margolin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas, Houston, TX 77030, USA
| | - Germán Rivas
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
| | - Begoña Monterroso
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
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21
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Zorrilla S, Monterroso B, Robles-Ramos MÁ, Margolin W, Rivas G. FtsZ Interactions and Biomolecular Condensates as Potential Targets for New Antibiotics. Antibiotics (Basel) 2021; 10:antibiotics10030254. [PMID: 33806332 PMCID: PMC7999717 DOI: 10.3390/antibiotics10030254] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 12/18/2022] Open
Abstract
FtsZ is an essential and central protein for cell division in most bacteria. Because of its ability to organize into dynamic polymers at the cell membrane and recruit other protein partners to form a “divisome”, FtsZ is a leading target in the quest for new antibacterial compounds. Strategies to potentially arrest the essential and tightly regulated cell division process include perturbing FtsZ’s ability to interact with itself and other divisome proteins. Here, we discuss the available methodologies to screen for and characterize those interactions. In addition to assays that measure protein-ligand interactions in solution, we also discuss the use of minimal membrane systems and cell-like compartments to better approximate the native bacterial cell environment and hence provide a more accurate assessment of a candidate compound’s potential in vivo effect. We particularly focus on ways to measure and inhibit under-explored interactions between FtsZ and partner proteins. Finally, we discuss recent evidence that FtsZ forms biomolecular condensates in vitro, and the potential implications of these assemblies in bacterial resistance to antibiotic treatment.
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Affiliation(s)
- Silvia Zorrilla
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain; (M.-Á.R.-R.); (G.R.)
- Correspondence: (S.Z.); (B.M.); Tel.: +34-91-837-3112 (S.Z. & B.M.)
| | - Begoña Monterroso
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain; (M.-Á.R.-R.); (G.R.)
- Correspondence: (S.Z.); (B.M.); Tel.: +34-91-837-3112 (S.Z. & B.M.)
| | - Miguel-Ángel Robles-Ramos
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain; (M.-Á.R.-R.); (G.R.)
| | - William Margolin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas, Houston, TX 77030, USA;
| | - Germán Rivas
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain; (M.-Á.R.-R.); (G.R.)
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22
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Hernández-Rocamora VM, Baranova N, Peters K, Breukink E, Loose M, Vollmer W. Real-time monitoring of peptidoglycan synthesis by membrane-reconstituted penicillin-binding proteins. eLife 2021; 10:61525. [PMID: 33625355 PMCID: PMC7943195 DOI: 10.7554/elife.61525] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 02/23/2021] [Indexed: 11/13/2022] Open
Abstract
Peptidoglycan is an essential component of the bacterial cell envelope that surrounds the cytoplasmic membrane to protect the cell from osmotic lysis. Important antibiotics such as β-lactams and glycopeptides target peptidoglycan biosynthesis. Class A penicillin-binding proteins (PBPs) are bifunctional membrane-bound peptidoglycan synthases that polymerize glycan chains and connect adjacent stem peptides by transpeptidation. How these enzymes work in their physiological membrane environment is poorly understood. Here, we developed a novel Förster resonance energy transfer-based assay to follow in real time both reactions of class A PBPs reconstituted in liposomes or supported lipid bilayers and applied this assay with PBP1B homologues from Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii in the presence or absence of their cognate lipoprotein activator. Our assay will allow unravelling the mechanisms of peptidoglycan synthesis in a lipid-bilayer environment and can be further developed to be used for high-throughput screening for new antimicrobials.
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Affiliation(s)
- Víctor M Hernández-Rocamora
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Natalia Baranova
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, University of Utrecht, Utrecht, Netherlands
| | - Martin Loose
- Institute for Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
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23
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Martini L, Brameyer S, Hoyer E, Jung K, Gerland U. Dynamics of chromosomal target search by a membrane-integrated one-component receptor. PLoS Comput Biol 2021; 17:e1008680. [PMID: 33539417 PMCID: PMC7888679 DOI: 10.1371/journal.pcbi.1008680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 02/17/2021] [Accepted: 01/07/2021] [Indexed: 12/03/2022] Open
Abstract
Membrane proteins account for about one third of the cellular proteome, but it is still unclear how dynamic they are and how they establish functional contacts with cytoplasmic interaction partners. Here, we consider a membrane-integrated one-component receptor that also acts as a transcriptional activator, and analyze how it kinetically locates its specific binding site on the genome. We focus on the case of CadC, the pH receptor of the acid stress response Cad system in E. coli. CadC is a prime example of a one-component signaling protein that directly binds to its cognate target site on the chromosome to regulate transcription. We combined fluorescence microscopy experiments, mathematical analysis, and kinetic Monte Carlo simulations to probe this target search process. Using fluorescently labeled CadC, we measured the time from activation of the receptor until successful binding to the DNA in single cells, exploiting that stable receptor-DNA complexes are visible as fluorescent spots. Our experimental data indicate that CadC is highly mobile in the membrane and finds its target by a 2D diffusion and capture mechanism. DNA mobility is constrained due to the overall chromosome organization, but a labeled DNA locus in the vicinity of the target site appears sufficiently mobile to randomly come close to the membrane. Relocation of the DNA target site to a distant position on the chromosome had almost no effect on the mean search time, which was between four and five minutes in either case. However, a mutant strain with two binding sites displayed a mean search time that was reduced by about a factor of two. This behavior is consistent with simulations of a coarse-grained lattice model for the coupled dynamics of DNA within a cell volume and proteins on its surface. The model also rationalizes the experimentally determined distribution of search times. Overall our findings reveal that DNA target search does not present a much bigger kinetic challenge for membrane-integrated proteins than for cytoplasmic proteins. More generally, diffusion and capture mechanisms may be sufficient for bacterial membrane proteins to establish functional contacts with cytoplasmic targets. Adaptation to changing environments is vital to bacteria and is enabled by sophisticated signal transduction systems. While signal transduction by two-component systems is well studied, the signal transduction of membrane-integrated one-component systems, where one protein performs both sensing and response regulation, are insufficiently understood. How can a membrane-integrated protein bind to specific sites on the genome to regulate transcription? Here, we study the kinetics of this process, which involves both protein diffusion within the membrane and conformational fluctuations of the genomic DNA. A well-suited model system for this question is CadC, the signaling protein of the E. coli Cad system involved in pH stress response. Fluorescently labeled CadC forms visible spots in single cells upon stable DNA-binding, marking the end of the protein-DNA search process. Moreover, the start of the search is triggered by a medium shift exposing cells to pH stress. We probe the underlying mechanism by varying the number and position of DNA target sites. We combine these experiments with mathematical analysis and kinetic Monte Carlo simulations of lattice models for the search process. Our results suggest that CadC diffusion in the membrane is pivotal for this search, while the DNA target site is just mobile enough to reach the membrane.
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Affiliation(s)
- Linda Martini
- Physics of Complex Biosystems, Technical University of Munich, Garching, Germany
| | - Sophie Brameyer
- Microbiology, Ludwig-Maximilians-University Munich, Martinsried, Germany
| | - Elisabeth Hoyer
- Microbiology, Ludwig-Maximilians-University Munich, Martinsried, Germany
| | - Kirsten Jung
- Microbiology, Ludwig-Maximilians-University Munich, Martinsried, Germany
- * E-mail: (KJ); (UG)
| | - Ulrich Gerland
- Physics of Complex Biosystems, Technical University of Munich, Garching, Germany
- * E-mail: (KJ); (UG)
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24
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Barrows JM, Goley ED. FtsZ dynamics in bacterial division: What, how, and why? Curr Opin Cell Biol 2021; 68:163-172. [PMID: 33220539 PMCID: PMC7925355 DOI: 10.1016/j.ceb.2020.10.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/19/2020] [Accepted: 10/21/2020] [Indexed: 01/06/2023]
Abstract
Bacterial cell division is orchestrated by the divisome, a protein complex centered on the tubulin homolog FtsZ. FtsZ polymerizes into a dynamic ring that defines the division site, recruits downstream proteins, and directs peptidoglycan synthesis to drive constriction. Recent studies have documented treadmilling of FtsZ polymer clusters both in cells and in vitro. Emerging evidence suggests that FtsZ dynamics are regulated largely by intrinsic properties of FtsZ itself and by the membrane anchoring protein FtsA. Although FtsZ dynamics are broadly required for Z-ring assembly, their role(s) during constriction may vary among bacterial species. These recent advances set the stage for future studies to investigate how FtsZ dynamics are physically and/or functionally coupled to peptidoglycan metabolic enzymes to direct efficient division.
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Affiliation(s)
- Jordan M Barrows
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Erin D Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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25
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McCausland JW, Yang X, Squyres GR, Lyu Z, Bruce KE, Lamanna MM, Söderström B, Garner EC, Winkler ME, Xiao J, Liu J. Treadmilling FtsZ polymers drive the directional movement of sPG-synthesis enzymes via a Brownian ratchet mechanism. Nat Commun 2021; 12:609. [PMID: 33504807 PMCID: PMC7840769 DOI: 10.1038/s41467-020-20873-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/15/2020] [Indexed: 01/30/2023] Open
Abstract
The FtsZ protein is a central component of the bacterial cell division machinery. It polymerizes at mid-cell and recruits more than 30 proteins to assemble into a macromolecular complex to direct cell wall constriction. FtsZ polymers exhibit treadmilling dynamics, driving the processive movement of enzymes that synthesize septal peptidoglycan (sPG). Here, we combine theoretical modelling with single-molecule imaging of live bacterial cells to show that FtsZ's treadmilling drives the directional movement of sPG enzymes via a Brownian ratchet mechanism. The processivity of the directional movement depends on the binding potential between FtsZ and the sPG enzyme, and on a balance between the enzyme's diffusion and FtsZ's treadmilling speed. We propose that this interplay may provide a mechanism to control the spatiotemporal distribution of active sPG enzymes, explaining the distinct roles of FtsZ treadmilling in modulating cell wall constriction rate observed in different bacteria.
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Affiliation(s)
- Joshua W McCausland
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Georgia R Squyres
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Zhixin Lyu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Kevin E Bruce
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Melissa M Lamanna
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Bill Söderström
- The ithree Institute, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
| | - Jian Liu
- Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
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26
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SPOR Proteins Are Required for Functionality of Class A Penicillin-Binding Proteins in Escherichia coli. mBio 2020; 11:mBio.02796-20. [PMID: 33144379 PMCID: PMC7642682 DOI: 10.1128/mbio.02796-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sporulation-related repeat (SPOR) domains are present in many bacterial cell envelope proteins and are known to bind peptidoglycan. Escherichia coli contains four SPOR proteins, DamX, DedD, FtsN, and RlpA, of which FtsN is essential for septal peptidoglycan synthesis. DamX and DedD may also play a role in cell division, based on mild cell division defects observed in strains lacking these SPOR domain proteins. Here, we show by nuclear magnetic resonance (NMR) spectroscopy that the periplasmic part of DedD consists of a disordered region followed by a canonical SPOR domain with a structure similar to that of the SPOR domains of FtsN, DamX, and RlpA. The absence of DamX or DedD decreases the functionality of the bifunctional transglycosylase-transpeptidase penicillin-binding protein 1B (PBP1B). DamX and DedD interact with PBP1B and stimulate its glycosyltransferase activity, and DamX also stimulates the transpeptidase activity. DedD also binds to PBP1A and stimulates its glycosyltransferase activity. Our data support a direct role of DamX and DedD in enhancing the activity of PBP1B and PBP1A, presumably during the synthesis of the cell division septum.IMPORTANCE Escherichia coli has four SPOR proteins that bind peptidoglycan, of which FtsN is essential for cell division. DamX and DedD are suggested to have semiredundant functions in cell division based on genetic evidence. Here, we solved the structure of the SPOR domain of DedD, and we show that both DamX and DedD interact with and stimulate the synthetic activity of the peptidoglycan synthases PBP1A and PBP1B, suggesting that these class A PBP enzymes act in concert with peptidoglycan-binding proteins during cell division.
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27
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Abstract
Bacteria surround their cell membrane with a net-like peptidoglycan layer, called sacculus, to protect the cell from bursting and maintain its cell shape. Sacculus growth during elongation and cell division is mediated by dynamic and transient multiprotein complexes, the elongasome and divisome, respectively. In this Review we present our current understanding of how peptidoglycan synthases are regulated by multiple and specific interactions with cell morphogenesis proteins that are linked to a dynamic cytoskeletal protein, either the actin-like MreB or the tubulin-like FtsZ. Several peptidoglycan synthases and hydrolases require activation by outer-membrane-anchored lipoproteins. We also discuss how bacteria achieve robust cell wall growth under different conditions and stresses by maintaining multiple peptidoglycan enzymes and regulators as well as different peptidoglycan growth mechanisms, and we present the emerging role of LD-transpeptidases in peptidoglycan remodelling.
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28
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Boguszewska K, Szewczuk M, Kaźmierczak-Barańska J, Karwowski BT. The Similarities between Human Mitochondria and Bacteria in the Context of Structure, Genome, and Base Excision Repair System. Molecules 2020; 25:E2857. [PMID: 32575813 PMCID: PMC7356350 DOI: 10.3390/molecules25122857] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 02/06/2023] Open
Abstract
Mitochondria emerged from bacterial ancestors during endosymbiosis and are crucial for cellular processes such as energy production and homeostasis, stress responses, cell survival, and more. They are the site of aerobic respiration and adenosine triphosphate (ATP) production in eukaryotes. However, oxidative phosphorylation (OXPHOS) is also the source of reactive oxygen species (ROS), which are both important and dangerous for the cell. Human mitochondria contain mitochondrial DNA (mtDNA), and its integrity may be endangered by the action of ROS. Fortunately, human mitochondria have repair mechanisms that allow protecting mtDNA and repairing lesions that may contribute to the occurrence of mutations. Mutagenesis of the mitochondrial genome may manifest in the form of pathological states such as mitochondrial, neurodegenerative, and/or cardiovascular diseases, premature aging, and cancer. The review describes the mitochondrial structure, genome, and the main mitochondrial repair mechanism (base excision repair (BER)) of oxidative lesions in the context of common features between human mitochondria and bacteria. The authors present a holistic view of the similarities of mitochondria and bacteria to show that bacteria may be an interesting experimental model for studying mitochondrial diseases, especially those where the mechanism of DNA repair is impaired.
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Affiliation(s)
| | | | | | - Bolesław T. Karwowski
- DNA Damage Laboratory of Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland; (K.B.); (M.S.); (J.K.-B.)
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29
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Abstract
The FtsZ protein is a highly conserved bacterial tubulin homolog. In vivo, the functional form of FtsZ is the polymeric, ring-like structure (Z-ring) assembled at the future division site during cell division. While it is clear that the Z-ring plays an essential role in orchestrating cytokinesis, precisely what its functions are and how these functions are achieved remain elusive. In this article, we review what we have learned during the past decade about the Z-ring's structure, function, and dynamics, with a particular focus on insights generated by recent high-resolution imaging and single-molecule analyses. We suggest that the major function of the Z-ring is to govern nascent cell pole morphogenesis by directing the spatiotemporal distribution of septal cell wall remodeling enzymes through the Z-ring's GTP hydrolysis-dependent treadmilling dynamics. In this role, FtsZ functions in cell division as the counterpart of the cell shape-determining actin homolog MreB in cell elongation.
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Affiliation(s)
- Ryan McQuillen
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA; ,
| | - Jie Xiao
- Department of Biophysics & Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA; ,
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30
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pH-dependent activation of cytokinesis modulates Escherichia coli cell size. PLoS Genet 2020; 16:e1008685. [PMID: 32203516 PMCID: PMC7117782 DOI: 10.1371/journal.pgen.1008685] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 04/02/2020] [Accepted: 02/19/2020] [Indexed: 01/21/2023] Open
Abstract
Cell size is a complex trait, derived from both genetic and environmental factors. Environmental determinants of bacterial cell size identified to date primarily target assembly of cytosolic components of the cell division machinery. Whether certain environmental cues also impact cell size through changes in the assembly or activity of extracytoplasmic division proteins remains an open question. Here, we identify extracellular pH as a modulator of cell division and a significant determinant of cell size across evolutionarily distant bacterial species. In the Gram-negative model organism Escherichia coli, our data indicate environmental pH impacts the length at which cells divide by altering the ability of the terminal cell division protein FtsN to localize to the cytokinetic ring where it activates division. Acidic environments lead to enrichment of FtsN at the septum and activation of division at a reduced cell length. Alkaline pH inhibits FtsN localization and suppresses division activation. Altogether, our work reveals a previously unappreciated role for pH in bacterial cell size control. Bacteria are constantly under assault from endogenous and environmental stressors. To ensure viability and reproductive fitness, many bacteria alter their growth and replication in response to stressful conditions. Previous work from many groups has identified regulatory mechanisms linking cell division with nutrient availability and metabolic state. However, comparatively little is known about how the cell division machinery responds to physical and chemical cues in the environment. Here, we identify a fundamental property of the extracellular environment—environmental pH—as a significant contributor to bacterial cell size. Our genetic and cytological data indicate pH-dependent changes in E. coli cell size are in part due to differential localization of the cell division activator FtsN across pH environments. Increased abundance of FtsN at midcell in acidic environments promotes cell division at a reduced cell volume, while decreased abundance of FtsN at midcell in alkaline environments effectively delays cell division until a larger size is reached. Altogether, our work identifies pH as an environmental determinant of E. coli cell division and illuminates FtsN recruitment as a mediator of cell size.
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Abstract
The polymerization-depolymerization dynamics of cytoskeletal proteins play essential roles in the self-organization of cytoskeletal structures, in eukaryotic as well as prokaryotic cells. While advances in fluorescence microscopy and in vitro reconstitution experiments have helped to study the dynamic properties of these complex systems, methods that allow to collect and analyze large quantitative datasets of the underlying polymer dynamics are still missing. Here, we present a novel image analysis workflow to study polymerization dynamics of active filaments in a nonbiased, highly automated manner. Using treadmilling filaments of the bacterial tubulin FtsZ as an example, we demonstrate that our method is able to specifically detect, track and analyze growth and shrinkage of polymers, even in dense networks of filaments. We believe that this automated method can facilitate the analysis of a large variety of dynamic cytoskeletal systems, using standard time-lapse movies obtained from experiments in vitro as well as in the living cell. Moreover, we provide scripts implementing this method as supplementary material.
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