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Pérez-Burgos M, Herfurth M, Kaczmarczyk A, Harms A, Huber K, Jenal U, Glatter T, Søgaard-Andersen L. A deterministic, c-di-GMP-dependent program ensures the generation of phenotypically similar, symmetric daughter cells during cytokinesis. Nat Commun 2024; 15:6014. [PMID: 39019889 PMCID: PMC11255338 DOI: 10.1038/s41467-024-50444-4] [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: 02/18/2024] [Accepted: 07/10/2024] [Indexed: 07/19/2024] Open
Abstract
Phenotypic heterogeneity in bacteria can result from stochastic processes or deterministic programs. The deterministic programs often involve the versatile second messenger c-di-GMP, and give rise to daughter cells with different c-di-GMP levels by deploying c-di-GMP metabolizing enzymes asymmetrically during cell division. By contrast, less is known about how phenotypic heterogeneity is kept to a minimum. Here, we identify a deterministic c-di-GMP-dependent program that is hardwired into the cell cycle of Myxococcus xanthus to minimize phenotypic heterogeneity and guarantee the formation of phenotypically similar daughter cells during division. Cells lacking the diguanylate cyclase DmxA have an aberrant motility behaviour. DmxA is recruited to the cell division site and its activity is switched on during cytokinesis, resulting in a transient increase in the c-di-GMP concentration. During cytokinesis, this c-di-GMP burst ensures the symmetric incorporation and allocation of structural motility proteins and motility regulators at the new cell poles of the two daughters, thereby generating phenotypically similar daughters with correct motility behaviours. Thus, our findings suggest a general c-di-GMP-dependent mechanism for minimizing phenotypic heterogeneity, and demonstrate that bacteria can ensure the formation of dissimilar or similar daughter cells by deploying c-di-GMP metabolizing enzymes to distinct subcellular locations.
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Affiliation(s)
- María Pérez-Burgos
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Marco Herfurth
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | | | - Andrea Harms
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Katrin Huber
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Urs Jenal
- Biozentrum, University of Basel, Basel, Switzerland
| | - Timo Glatter
- Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
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2
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Black ME, Fei C, Alert R, Wingreen NS, Shaevitz JW. Capillary interactions drive the self-organization of bacterial colonies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.28.596252. [PMID: 38853967 PMCID: PMC11160631 DOI: 10.1101/2024.05.28.596252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Many bacteria inhabit thin layers of water on solid surfaces both naturally in soils or on hosts or textiles and in the lab on agar hydrogels. In these environments, cells experience capillary forces, yet an understanding of how these forces shape bacterial collective behaviors remains elusive. Here, we show that the water menisci formed around bacteria lead to capillary attraction between cells while still allowing them to slide past one another. We develop an experimental apparatus that allows us to control bacterial collective behaviors by varying the strength and range of capillary forces. Combining 3D imaging and cell tracking with agent-based modeling, we demonstrate that capillary attraction organizes rod-shaped bacteria into densely packed, nematic groups, and profoundly influences their collective dynamics and morphologies. Our results suggest that capillary forces may be a ubiquitous physical ingredient in shaping microbial communities in partially hydrated environments.
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Meng Y, Zhang X, Zhai Y, Li Y, Shao Z, Liu S, Zhang C, Xing XH, Zheng H. Identification of the mutual gliding locus as a factor for gut colonization in non-native bee hosts using the ARTP mutagenesis. MICROBIOME 2024; 12:93. [PMID: 38778376 PMCID: PMC11112851 DOI: 10.1186/s40168-024-01813-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/09/2024] [Indexed: 05/25/2024]
Abstract
BACKGROUND The gut microbiota and their hosts profoundly affect each other's physiology and evolution. Identifying host-selected traits is crucial to understanding the processes that govern the evolving interactions between animals and symbiotic microbes. Current experimental approaches mainly focus on the model bacteria, like hypermutating Escherichia coli or the evolutionary changes of wild stains by host transmissions. A method called atmospheric and room temperature plasma (ARTP) may overcome the bottleneck of low spontaneous mutation rates while maintaining mild conditions for the gut bacteria. RESULTS We established an experimental symbiotic system with gnotobiotic bee models to unravel the molecular mechanisms promoting host colonization. By in vivo serial passage, we tracked the genetic changes of ARTP-treated Snodgrassella strains from Bombus terrestris in the non-native honeybee host. We observed that passaged isolates showing genetic changes in the mutual gliding locus have a competitive advantage in the non-native host. Specifically, alleles in the orphan mglB, the GTPase activating protein, promoted colonization potentially by altering the type IV pili-dependent motility of the cells. Finally, competition assays confirmed that the mutations out-competed the ancestral strain in the non-native honeybee gut but not in the native host. CONCLUSIONS Using the ARTP mutagenesis to generate a mutation library of gut symbionts, we explored the potential genetic mechanisms for improved gut colonization in non-native hosts. Our findings demonstrate the implication of the cell mutual-gliding motility in host association and provide an experimental system for future study on host-microbe interactions. Video Abstract.
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Affiliation(s)
- Yujie Meng
- Faculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China
- MGI Tech, Qingdao, 266426, China
| | - Xue Zhang
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100083, China
| | - Yifan Zhai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, 250100, China
| | - Yuan Li
- MGI Tech, Qingdao, 266426, China
| | | | | | - Chong Zhang
- Department of Chemical Engineering, Institute of Biochemical Engineering, Tsinghua University, Beijing, 100084, China
| | - Xin-Hui Xing
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Hao Zheng
- Faculty of Food Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, China.
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Carreira LAM, Szadkowski D, Lometto S, Hochberg GKA, Søgaard-Andersen L. Molecular basis and design principles of switchable front-rear polarity and directional migration in Myxococcus xanthus. Nat Commun 2023; 14:4056. [PMID: 37422455 PMCID: PMC10329633 DOI: 10.1038/s41467-023-39773-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 06/28/2023] [Indexed: 07/10/2023] Open
Abstract
During cell migration, front-rear polarity is spatiotemporally regulated; however, the underlying design of regulatory interactions varies. In rod-shaped Myxococcus xanthus cells, a spatial toggle switch dynamically regulates front-rear polarity. The polarity module establishes front-rear polarity by guaranteeing front pole-localization of the small GTPase MglA. Conversely, the Frz chemosensory system, by acting on the polarity module, causes polarity inversions. MglA localization depends on the RomR/RomX GEF and MglB/RomY GAP complexes that localize asymmetrically to the poles by unknown mechanisms. Here, we show that RomR and the MglB and MglC roadblock domain proteins generate a positive feedback by forming a RomR/MglC/MglB complex, thereby establishing the rear pole with high GAP activity that is non-permissive to MglA. MglA at the front engages in negative feedback that breaks the RomR/MglC/MglB positive feedback allosterically, thus ensuring low GAP activity at this pole. These findings unravel the design principles of a system for switchable front-rear polarity.
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Affiliation(s)
| | - Dobromir Szadkowski
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | - Stefano Lometto
- Evolutionary Biochemistry Group, Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany
- Department of Chemistry and Center for Synthetic Microbiology, Philipps University, 35043, Marburg, Germany
| | - Georg K A Hochberg
- Evolutionary Biochemistry Group, Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany
- Department of Chemistry and Center for Synthetic Microbiology, Philipps University, 35043, Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
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5
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Dinet C, Mignot T. Unorthodox regulation of the MglA Ras-like GTPase controlling polarity in Myxococcus xanthus. FEBS Lett 2023; 597:850-864. [PMID: 36520515 DOI: 10.1002/1873-3468.14565] [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: 10/21/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Motile cells have developed a large array of molecular machineries to actively change their direction of movement in response to spatial cues from their environment. In this process, small GTPases act as molecular switches and work in tandem with regulators and sensors of their guanine nucleotide status (GAP, GEF, GDI and effectors) to dynamically polarize the cell and regulate its motility. In this review, we focus on Myxococcus xanthus as a model organism to elucidate the function of an atypical small Ras GTPase system in the control of directed cell motility. M. xanthus cells direct their motility by reversing their direction of movement through a mechanism involving the redirection of the motility apparatus to the opposite cell pole. The reversal frequency of moving M. xanthus cells is controlled by modular and interconnected protein networks linking the chemosensory-like frizzy (Frz) pathway - that transmits environmental signals - to the downstream Ras-like Mgl polarity control system - that comprises the Ras-like MglA GTPase protein and its regulators. Here, we discuss how variations in the GTPase interactome landscape underlie single-cell decisions and consequently, multicellular patterns.
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Affiliation(s)
- Céline Dinet
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, France
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Szadkowski D, Carreira LAM, Søgaard-Andersen L. A bipartite, low-affinity roadblock domain-containing GAP complex regulates bacterial front-rear polarity. PLoS Genet 2022; 18:e1010384. [PMID: 36067225 PMCID: PMC9481161 DOI: 10.1371/journal.pgen.1010384] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 09/16/2022] [Accepted: 08/17/2022] [Indexed: 11/29/2022] Open
Abstract
The Ras-like GTPase MglA is a key regulator of front-rear polarity in the rod-shaped Myxococcus xanthus cells. MglA-GTP localizes to the leading cell pole and stimulates assembly of the two machineries for type IV pili-dependent motility and gliding motility. MglA-GTP localization is spatially constrained by its cognate GEF, the RomR/RomX complex, and GAP, the MglB Roadblock-domain protein. Paradoxically, RomR/RomX and MglB localize similarly with low and high concentrations at the leading and lagging poles, respectively. Yet, GEF activity dominates at the leading and GAP activity at the lagging pole by unknown mechanisms. Here, we identify RomY and show that it stimulates MglB GAP activity. The MglB/RomY interaction is low affinity, restricting formation of the bipartite MglB/RomY GAP complex almost exclusively to the lagging pole with the high MglB concentration. Our data support a model wherein RomY, by forming a low-affinity complex with MglB, ensures that the high MglB/RomY GAP activity is confined to the lagging pole where it dominates and outcompetes the GEF activity of the RomR/RomX complex. Thereby, MglA-GTP localization is constrained to the leading pole establishing front-rear polarity. Bacterial cells are spatially highly organized with proteins localizing to distinct subcellular locations. This spatial organization, or cell polarity, is important for many cellular processes including motility. The rod-shaped M. xanthus cells move with defined leading and lagging cell poles. This front-rear polarity is brought about by the polarity module, which consists of the small Ras-like GTPase MglA, its GEF (the RomR/RomX complex) and its GAP (MglB). Specifically, MglA-GTP localizes to the leading pole and stimulates assembly of the motility machineries. MglA-GTP localization, in turn, is spatially constrained by its GEF and GAP. Paradoxically, the RomR/RomX GEF and MglB GAP localize similarly with low and high concentrations at the leading and lagging poles, respectively. Yet, GEF activity dominates at the leading and GAP activity at the lagging pole. Here, we identify RomY and show that it stimulates MglB GAP activity. Interestingly, the MglB/RomY interaction is low affinity. Consequently, MglB/RomY complex formation almost exclusively occurs at the lagging cell pole with the high MglB concentration. Thus, the key to precisely stimulating MglB GAP activity only at the lagging pole is that the MglB/RomY interaction is low-affinity, ultimately restricting MglA-GTP to the leading pole.
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Affiliation(s)
- Dobromir Szadkowski
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | | | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- * E-mail:
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7
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Carreira LAM, Szadkowski D, Müller F, Søgaard-Andersen L. Spatiotemporal regulation of switching front–rear cell polarity. Curr Opin Cell Biol 2022; 76:102076. [DOI: 10.1016/j.ceb.2022.102076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/17/2022] [Accepted: 02/24/2022] [Indexed: 11/30/2022]
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Three PilZ Domain Proteins, PlpA, PixA, and PixB, Have Distinct Functions in Regulation of Motility and Development in Myxococcus xanthus. J Bacteriol 2021; 203:e0012621. [PMID: 33875546 PMCID: PMC8316039 DOI: 10.1128/jb.00126-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In bacteria, the nucleotide-based second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) binds to effectors to generate outputs in response to changes in the environment. In Myxococcus xanthus, c-di-GMP regulates type IV pilus-dependent motility and the starvation-induced developmental program that results in formation of spore-filled fruiting bodies; however, little is known about the effectors that bind c-di-GMP. Here, we systematically inactivated all 24 genes encoding PilZ domain-containing proteins, which are among the most common c-di-GMP effectors. We confirm that the stand-alone PilZ domain protein PlpA is important for regulation of motility independently of the Frz chemosensory system and that Pkn1, which is composed of a Ser/Thr kinase domain and a PilZ domain, is specifically important for development. Moreover, we identify two PilZ domain proteins that have distinct functions in regulating motility and development. PixB, which is composed of two PilZ domains and an acetyltransferase domain, binds c-di-GMP in vitro and regulates type IV pilus-dependent and gliding motility in a Frz-dependent manner as well as development. The acetyltransferase domain is required and sufficient for function during growth, while all three domains and c-di-GMP binding are essential for PixB function during development. PixA is a response regulator composed of a PilZ domain and a receiver domain, binds c-di-GMP in vitro, and regulates motility independently of the Frz system, likely by setting up the polarity of the two motility systems. Our results support a model whereby PlpA, PixA, and PixB act in independent pathways and have distinct functions in regulation of motility. IMPORTANCE c-di-GMP signaling controls bacterial motility in many bacterial species by binding to downstream effector proteins. Here, we identify two PilZ domain-containing proteins in Myxococcus xanthus that bind c-di-GMP. We show that PixB, which contains two PilZ domains and an acetyltransferase domain, acts in a manner that depends on the Frz chemosensory system to regulate motility via the acetyltransferase domain, while the intact protein and c-di-GMP binding are essential for PixB to support development. In contrast, PixA acts in a Frz-independent manner to regulate motility. Taking our results together with previous observations, we conclude that PilZ domain proteins and c-di-GMP act in multiple independent pathways to regulate motility and development in M. xanthus.
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9
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Zhang H, Venkatesan S, Nan B. Myxococcus xanthus as a Model Organism for Peptidoglycan Assembly and Bacterial Morphogenesis. Microorganisms 2021; 9:microorganisms9050916. [PMID: 33923279 PMCID: PMC8144978 DOI: 10.3390/microorganisms9050916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 11/16/2022] Open
Abstract
A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis, because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.
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Pinheiro B, Scheidler CM, Kielkowski P, Schmid M, Forné I, Ye S, Reiling N, Takano E, Imhof A, Sieber SA, Schneider S, Jung K. Structure and Function of an Elongation Factor P Subfamily in Actinobacteria. Cell Rep 2021; 30:4332-4342.e5. [PMID: 32234471 DOI: 10.1016/j.celrep.2020.03.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 02/06/2020] [Accepted: 03/02/2020] [Indexed: 12/28/2022] Open
Abstract
Translation of consecutive proline motifs causes ribosome stalling and requires rescue via the action of a specific translation elongation factor, EF-P in bacteria and archaeal/eukaryotic a/eIF5A. In Eukarya, Archaea, and all bacteria investigated so far, the functionality of this translation elongation factor depends on specific and rather unusual post-translational modifications. The phylum Actinobacteria, which includes the genera Corynebacterium, Mycobacterium, and Streptomyces, is of both medical and economic significance. Here, we report that EF-P is required in these bacteria in particular for the translation of proteins involved in amino acid and secondary metabolite production. Notably, EF-P of Actinobacteria species does not need any post-translational modification for activation. While the function and overall 3D structure of this EF-P type is conserved, the loop containing the conserved lysine is flanked by two essential prolines that rigidify it. Actinobacteria's EF-P represents a unique subfamily that works without any modification.
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Affiliation(s)
- Bruno Pinheiro
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | | | - Pavel Kielkowski
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Marina Schmid
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Ignasi Forné
- Biomedical Center Munich, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Suhui Ye
- Manchester Institute of Biotechnology, Department of Chemistry, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, UK
| | - Norbert Reiling
- RG Microbial Interface Biology, Research Center Borstel, Leibniz Lung Center, Borstel, Germany; German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Borstel, Germany
| | - Eriko Takano
- Manchester Institute of Biotechnology, Department of Chemistry, School of Natural Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, UK
| | - Axel Imhof
- Biomedical Center Munich, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Stephan A Sieber
- Department of Chemistry, Technische Universität München, Garching, Germany
| | - Sabine Schneider
- Department of Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany.
| | - Kirsten Jung
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany.
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Dinet C, Michelot A, Herrou J, Mignot T. Linking single-cell decisions to collective behaviours in social bacteria. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190755. [PMID: 33487114 DOI: 10.1098/rstb.2019.0755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Social bacteria display complex behaviours whereby thousands of cells collectively and dramatically change their form and function in response to nutrient availability and changing environmental conditions. In this review, we focus on Myxococcus xanthus motility, which supports spectacular transitions based on prey availability across its life cycle. A large body of work suggests that these behaviours require sensory capacity implemented at the single-cell level. Focusing on recent genetic work on a core cellular pathway required for single-cell directional decisions, we argue that signal integration, multi-modal sensing and memory are at the root of decision making leading to multicellular behaviours. Hence, Myxococcus may be a powerful biological system to elucidate how cellular building blocks cooperate to form sensory multicellular assemblages, a possible origin of cognitive mechanisms in biological systems. This article is part of the theme issue 'Basal cognition: conceptual tools and the view from the single cell'.
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Affiliation(s)
- Céline Dinet
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, 31 Chemin Joseph Aiguier, 13009 Marseille, France.,Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Alphée Michelot
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Julien Herrou
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, 31 Chemin Joseph Aiguier, 13009 Marseille, France
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12
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Kapoor S, Kodesia A, Kalidas N, Ashish, Thakur KG. Structural characterization of Myxococcus xanthus MglC, a component of the polarity control system, and its interactions with its paralog MglB. J Biol Chem 2021; 296:100308. [PMID: 33493516 PMCID: PMC7949163 DOI: 10.1016/j.jbc.2021.100308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 11/28/2022] Open
Abstract
The δ-proteobacteria Myxococcus xanthus displays social (S) and adventurous (A) motilities, which require pole-to-pole reversal of the motility regulator proteins. Mutual gliding motility protein C (MglC), a paralog of GTPase-activating protein Mutual gliding motility protein B (MglB), is a member of the polarity module involved in regulating motility. However, little is known about the structure and function of MglC. Here, we determined ∼1.85 Å resolution crystal structure of MglC using Selenomethionine Single-wavelength anomalous diffraction. The crystal structure revealed that, despite sharing <9% sequence identity, both MglB and MglC adopt a Regulatory Light Chain 7 family fold. However, MglC has a distinct ∼30° to 40° shift in the orientation of the functionally important α2 helix compared with other structural homologs. Using isothermal titration calorimetry and size-exclusion chromatography, we show that MglC binds MglB in 2:4 stoichiometry with submicromolar range dissociation constant. Using small-angle X-ray scattering and molecular docking studies, we show that the MglBC complex consists of a MglC homodimer sandwiched between two homodimers of MglB. A combination of size-exclusion chromatography and site-directed mutagenesis studies confirmed the MglBC interacting interface obtained by molecular docking studies. Finally, we show that the C-terminal region of MglB, crucial for binding its established partner MglA, is not required for binding MglC. These studies suggest that the MglB uses distinct interfaces to bind MglA and MglC. Based on these data, we propose a model suggesting a new role for MglC in polarity reversal in M. xanthus.
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Affiliation(s)
- Srajan Kapoor
- Structural Biology Laboratory, Council of Scientific and Industrial Research-Institute of Microbial Technology, G. N. Ramachandran Protein Centre, Chandigarh, India
| | - Akriti Kodesia
- Structural Biology Laboratory, Council of Scientific and Industrial Research-Institute of Microbial Technology, G. N. Ramachandran Protein Centre, Chandigarh, India
| | - Nidhi Kalidas
- Council of Scientific and Industrial Research-Institute of Microbial Technology, G. N. Ramachandran Protein Centre, Chandigarh, India
| | - Ashish
- Council of Scientific and Industrial Research-Institute of Microbial Technology, G. N. Ramachandran Protein Centre, Chandigarh, India
| | - Krishan Gopal Thakur
- Structural Biology Laboratory, Council of Scientific and Industrial Research-Institute of Microbial Technology, G. N. Ramachandran Protein Centre, Chandigarh, India.
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13
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The small GTPase MglA together with the TPR domain protein SgmX stimulates type IV pili formation in M. xanthus. Proc Natl Acad Sci U S A 2020; 117:23859-23868. [PMID: 32900945 PMCID: PMC7519303 DOI: 10.1073/pnas.2004722117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many bacteria move across surfaces using type IV pili (T4P). The piliation pattern varies between species; however, the underlying mechanisms governing these patterns remain largely unknown. Here, we demonstrate that in the rod-shaped Myxococcus xanthus cells, the unipolar formation of T4P at the leading cell pole is the result of stimulation by the small GTPase MglA together with the effector protein SgmX, while MglB, the cognate MglA GTPase activating protein (GAP) that localizes to the lagging cell pole, blocks this stimulation at the lagging pole due to its GAP activity. During reversals, MglA/SgmX and MglB switch polarity, laying the foundation for T4P formation at the new leading cell pole and inhibition of T4P formation at the former leading cell pole. Bacteria can move across surfaces using type IV pili (T4P), which undergo cycles of extension, adhesion, and retraction. The T4P localization pattern varies between species; however, the underlying mechanisms are largely unknown. In the rod-shaped Myxococcus xanthus cells, T4P localize at the leading cell pole. As cells reverse their direction of movement, T4P are disassembled at the old leading pole and then form at the new leading pole. Thus, cells can form T4P at both poles but engage only one pole at a time in T4P formation. Here, we address how this T4P unipolarity is realized. We demonstrate that the small Ras-like GTPase MglA stimulates T4P formation in its GTP-bound state by direct interaction with the tetratricopeptide repeat (TPR) domain-containing protein SgmX. SgmX, in turn, is important for polar localization of the T4P extension ATPase PilB. The cognate MglA GTPase activating protein (GAP) MglB, which localizes mainly to the lagging cell pole, indirectly blocks T4P formation at this pole by stimulating the conversion of MglA-GTP to MglA-GDP. Based on these findings, we propose a model whereby T4P unipolarity is accomplished by stimulation of T4P formation at the leading pole by MglA-GTP and SgmX and indirect inhibition of T4P formation at the lagging pole by MglB due to its MglA GAP activity. During reversals, MglA, SgmX, and MglB switch polarity, thus laying the foundation for T4P formation at the new leading pole and inhibition of T4P formation at the new lagging pole.
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Carreira LAM, Tostevin F, Gerland U, Søgaard-Andersen L. Protein-protein interaction network controlling establishment and maintenance of switchable cell polarity. PLoS Genet 2020; 16:e1008877. [PMID: 32569324 PMCID: PMC7332107 DOI: 10.1371/journal.pgen.1008877] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/02/2020] [Accepted: 05/21/2020] [Indexed: 11/19/2022] Open
Abstract
Cell polarity underlies key processes in all cells, including growth, differentiation and division. In the bacterium Myxococcus xanthus, front-rear polarity is crucial for motility. Notably, this polarity can be inverted, independent of the cell-cycle, by chemotactic signaling. However, a precise understanding of the protein network that establishes polarity and allows for its inversion has remained elusive. Here, we use a combination of quantitative experiments and data-driven theory to unravel the complex interplay between the three key components of the M. xanthus polarity module. By studying each of these components in isolation and their effects as we systematically reconstruct the system, we deduce the network of effective interactions between the polarity proteins. RomR lies at the root of this network, promoting polar localization of the other components, while polarity arises from interconnected negative and positive feedbacks mediated by the small GTPase MglA and its cognate GAP MglB, respectively. We rationalize this network topology as operating as a spatial toggle switch, providing stable polarity for persistent cell movement whilst remaining responsive to chemotactic signaling and thus capable of polarity inversions. Our results have implications not only for the understanding of polarity and motility in M. xanthus but also, more broadly, for dynamic cell polarity. The asymmetric localization of cellular components (polarity) is at the core of many important cellular functions including growth, division, differentiation and motility. However, important questions still remain regarding the design principles underlying polarity networks and how their activity can be controlled in space and time. We use the rod-shaped bacterium Myxococcus xanthus as a model to study polarity and its regulation. Like many bacteria, in M. xanthus a well-defined front-rear polarity axis enables efficient translocation. This polarity axis is defined by asymmetric polar localization of a switch-like GTPase and its cognate regulators, and can be reversed in response to signaling cues. Here we use a combination of quantitative experiments and data-driven theory to deduce the network of interactions among the M. xanthus polarity proteins and to show how the combination of positive- and negative-feedback interactions give rise to asymmetric polar protein localization. We rationalize this network topology as operating as a spatial toggle switch, providing stable polarity for persistent cell movement whilst remaining responsive to chemotactic signaling and capable of polarity inversions. Our results have broader implications for our understanding of dynamic cell polarity and GTPase regulation in both bacteria and eukaryotic cells.
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Affiliation(s)
| | - Filipe Tostevin
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Physik-Department, Technische Universität München, James Franck Straße, Garching, Germany
| | - Ulrich Gerland
- Physik-Department, Technische Universität München, James Franck Straße, Garching, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- * E-mail:
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15
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Establishing rod shape from spherical, peptidoglycan-deficient bacterial spores. Proc Natl Acad Sci U S A 2020; 117:14444-14452. [PMID: 32513721 DOI: 10.1073/pnas.2001384117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Chemical-induced spores of the Gram-negative bacterium Myxococcus xanthus are peptidoglycan (PG)-deficient. It is unclear how these spherical spores germinate into rod-shaped, walled cells without preexisting PG templates. We found that germinating spores first synthesize PG randomly on spherical surfaces. MglB, a GTPase-activating protein, forms a cluster that responds to the status of PG growth and stabilizes at one future cell pole. Following MglB, the Ras family GTPase MglA localizes to the second pole. MglA directs molecular motors to transport the bacterial actin homolog MreB and the Rod PG synthesis complexes away from poles. The Rod system establishes rod shape de novo by elongating PG at nonpolar regions. Thus, similar to eukaryotic cells, the interactions between GTPase, cytoskeletons, and molecular motors initiate spontaneous polarization in bacteria.
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16
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MglA functions as a three-state GTPase to control movement reversals of Myxococcus xanthus. Nat Commun 2019; 10:5300. [PMID: 31757955 PMCID: PMC6876712 DOI: 10.1038/s41467-019-13274-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/24/2019] [Indexed: 01/30/2023] Open
Abstract
In Myxococcus xanthus, directed movement is controlled by pole-to-pole oscillations of the small GTPase MglA and its GAP MglB. Direction reversals require that MglA is inactivated by MglB, yet paradoxically MglA and MglB are located at opposite poles at reversal initiation. Here we report the complete MglA/MglB structural cycle combined to GAP kinetics and in vivo motility assays, which uncovers that MglA is a three-state GTPase and suggests a molecular mechanism for concerted MglA/MglB relocalizations. We show that MglA has an atypical GTP-bound state (MglA-GTP*) that is refractory to MglB and is re-sensitized by a feedback mechanism operated by MglA-GDP. By identifying and mutating the pole-binding region of MglB, we then provide evidence that the MglA-GTP* state exists in vivo. These data support a model in which MglA-GDP acts as a soluble messenger to convert polar MglA-GTP* into a diffusible MglA-GTP species that re-localizes to the opposite pole during reversals. In Myxococcus xanthus, directed movement is controlled by pole-to-pole oscillations of the small GTPase MglA and its GAP MglB. Here authors report the complete MglA/MglB structural cycle and uncover that MglA is a three-state GTPase that adopts an atypical GTP-bound state that is refractory to inactivation by MglB.
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17
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Herrou J, Mignot T. Dynamic polarity control by a tunable protein oscillator in bacteria. Curr Opin Cell Biol 2019; 62:54-60. [PMID: 31627169 DOI: 10.1016/j.ceb.2019.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/09/2019] [Accepted: 09/05/2019] [Indexed: 01/30/2023]
Abstract
In bacteria, cell polarization involves the controlled targeting of specific proteins to the poles, defining polar identity and function. How a specific protein is targeted to one pole and what are the processes that facilitate its dynamic relocalization to the opposite pole is still unclear. The Myxococcus xanthus polarization example illustrates how the dynamic and asymmetric localization of polar proteins enable a controlled and fast switch of polarity. In M. xanthus, the opposing polar distribution of the small GTPase MglA and its cognate activating protein MglB defines the direction of movement of the cell. During a reversal event, the switch of direction is triggered by the Frz chemosensory system, which controls polarity reversals through a so-called gated relaxation oscillator. In this review, we discuss how this genetic architecture can provoke sharp behavioral transitions depending on Frz activation levels, which is central to multicellular behaviors in this bacterium.
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Affiliation(s)
- Julien Herrou
- Laboratoire de Chimie Bactérienne, CNRS - Aix Marseille University UMR 7283, Institut de Microbiologie de la Méditerranée, Marseille, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, CNRS - Aix Marseille University UMR 7283, Institut de Microbiologie de la Méditerranée, Marseille, France.
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18
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Allosteric regulation of a prokaryotic small Ras-like GTPase contributes to cell polarity oscillations in bacterial motility. PLoS Biol 2019; 17:e3000459. [PMID: 31560685 PMCID: PMC6785124 DOI: 10.1371/journal.pbio.3000459] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/09/2019] [Accepted: 09/04/2019] [Indexed: 11/25/2022] Open
Abstract
Mutual gliding motility A (MglA), a small Ras-like GTPase; Mutual gliding motility B (MglB), its GTPase activating protein (GAP); and Required for Motility Response Regulator (RomR), a protein that contains a response regulator receiver domain, are major components of a GTPase-dependent biochemical oscillator that drives cell polarity reversals in the bacterium Myxococcus xanthus. We report the crystal structure of a complex of M. xanthus MglA and MglB, which reveals that the C-terminal helix (Ct-helix) from one protomer of the dimeric MglB binds to a pocket distal to the active site of MglA. MglB increases the GTPase activity of MglA by reorientation of key catalytic residues of MglA (a GAP function) combined with allosteric regulation of nucleotide exchange by the Ct-helix (a guanine nucleotide exchange factor [GEF] function). The dual GAP-GEF activities of MglB accelerate the rate of GTP hydrolysis over multiple enzymatic cycles. Consistent with its GAP and GEF activities, MglB interacts with MglA bound to either GTP or GDP. The regulation is essential for cell polarity, because deletion of the Ct-helix causes bipolar localization of MglA, MglB, and RomR, thereby causing reversal defects in M. xanthus. A bioinformatics analysis reveals the presence of Ct-helix in homologues of MglB in other bacterial phyla, suggestive of the prevalence of the allosteric mechanism among other prokaryotic small Ras-like GTPases. A study on the mechanism of cell polarity oscillations in Myxococcus xanthus reveals a novel allosteric regulatory mechanism for a small Ras-like GTPase. The motility protein MglB is the first example of both GTPase activating protein (GAP) and guanosine nucleotide exchange factor (GEF) activities being integrated into a single regulator of the small Ras-like GTPase MglA.
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19
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Spatial control of the GTPase MglA by localized RomR–RomX GEF and MglB GAP activities enables Myxococcus xanthus motility. Nat Microbiol 2019; 4:1344-1355. [DOI: 10.1038/s41564-019-0451-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 04/08/2019] [Indexed: 11/08/2022]
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20
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Lowry RC, Milner DS, Al-Bayati AMS, Lambert C, Francis VI, Porter SL, Sockett RE. Evolutionary diversification of the RomR protein of the invasive deltaproteobacterium, Bdellovibrio bacteriovorus. Sci Rep 2019; 9:5007. [PMID: 30899045 PMCID: PMC6428892 DOI: 10.1038/s41598-019-41263-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/27/2019] [Indexed: 01/19/2023] Open
Abstract
Bdellovibrio bacteriovorus is a predatory deltaproteobacterium that encounters individual Gram-negative prey bacteria with gliding or swimming motility, and then is able to invade such prey cells via type IVa pilus-dependent mechanisms. Movement control (pili or gliding) in other deltaproteobacteria, such as the pack hunting Myxococcus xanthus, uses a response regulator protein, RomRMx (which dynamically relocalises between the cell poles) and a GTPase, MglAMx, previously postulated as an interface between the FrzMx chemosensory system and gliding or pilus-motility apparatus, to produce regulated bidirectional motility. In contrast, B. bacteriovorus predation is a more singular encounter between a lone predator and prey; contact is always via the piliated, non-flagellar pole of the predator, involving MglABd, but no Frz system. In this new study, tracking fluorescent RomRBd microscopically during predatory growth shows that it does not dynamically relocalise, in contrast to the M. xanthus protein; instead having possible roles in growth events. Furthermore, transcriptional start analysis, site-directed mutagenesis and bacterial two-hybrid interaction studies, indicate an evolutionary loss of RomRBd activation (via receiver domain phosphorylation) in this lone hunting bacterium, demonstrating divergence from its bipolar role in motility in pack-hunting M. xanthus and further evolution that may differentiate lone from pack predators.
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Affiliation(s)
- Rebecca C Lowry
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - David S Milner
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.,Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Asmaa M S Al-Bayati
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.,Northern Technical University, Mosul, Iraq
| | - Carey Lambert
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Vanessa I Francis
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Steven L Porter
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.
| | - R E Sockett
- School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
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21
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Abstract
Spatial organization is a hallmark of all living systems. Even bacteria, the smallest forms of cellular life, display defined shapes and complex internal organization, showcasing a highly structured genome, cytoskeletal filaments, localized scaffolding structures, dynamic spatial patterns, active transport, and occasionally, intracellular organelles. Spatial order is required for faithful and efficient cellular replication and offers a powerful means for the development of unique biological properties. Here, we discuss organizational features of bacterial cells and highlight how bacteria have evolved diverse spatial mechanisms to overcome challenges cells face as self-replicating entities.
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22
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A gated relaxation oscillator mediated by FrzX controls morphogenetic movements in Myxococcus xanthus. Nat Microbiol 2018; 3:948-959. [PMID: 30013238 DOI: 10.1038/s41564-018-0203-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 06/21/2018] [Indexed: 11/09/2022]
Abstract
Dynamic control of cell polarity is of critical importance for many aspects of cellular development and motility. In Myxococcus xanthus, MglA, a G protein, and MglB, its cognate GTPase-activating protein, establish a polarity axis that defines the direction of movement of the cell and that can be rapidly inverted by the Frz chemosensory system. Although vital for collective cell behaviours, how Frz triggers this switch has remained unknown. Here, we use genetics, imaging and mathematical modelling to show that Frz controls polarity reversals via a gated relaxation oscillator. FrzX, which we identify as a target of the Frz kinase, provides the gating and thus acts as the trigger for reversals. Slow relocalization of the polarity protein RomR then creates a refractory period during which another switch cannot be triggered. A secondary Frz output, FrzZ, decreases this delay, allowing rapid reversals when required. Thus, this architecture results in a highly tuneable switch that allows a wide range of reversal frequencies.
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23
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Comparative Genomics of Myxobacterial Chemosensory Systems. J Bacteriol 2018; 200:JB.00620-17. [PMID: 29158239 DOI: 10.1128/jb.00620-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 10/26/2017] [Indexed: 11/20/2022] Open
Abstract
Chemosensory systems (CSS) are among the most complex organizations of proteins functioning cooperatively to regulate bacterial motility and other cellular activities. These systems have been studied extensively in bacteria, and usually, they are present as a single system. Eight CSS, the highest number in bacteria, have been reported in Myxococcus xanthus DK1622 and are involved in coordinating diverse functions. Here, we have explored and compared the CSS in all available genomes of order Myxococcales. Myxococcales members contain 97 to 476 two-component system (TCS) proteins, which assist the bacteria in surviving and adapting to varying environmental conditions. The number of myxobacterial CSS ranges between 1 and 12, with the largest number in family Cystobacteraceae and the smallest in Nannocystaceae CheA protein was used as a phylogenetic marker to infer evolutionary relatedness between different CSS, and six novel CSS ("extra CSS" [ECSS]) were thus identified in the myxobacteria besides the previously reported Che1 to Che8 systems from M. xanthus Che1 to Che8 systems are monophyletic to deltaproteobacteria, whereas the newly identified ECSS form separate clades with different bacterial classes. The comparative modular organization was concordant with the phylogeny. Four clusters lacking CheA proteins were also identified via CheB-based phylogenetic analysis and were categorized as accessory CSS (ACSS). In Archangium, an orphan CSS was identified, in which both CheA and CheB were absent. The novel, accessory, and orphan multimodular CSS identified here suggest the emergence of myxobacterial CSS and could assist in further characterizing their roles.IMPORTANCE This study is focused on chemosensory systems (CSS), which help the bacterium in directing its movement toward or away from chemical gradients. CSS are present as a single system in most of the bacteria except in some groups, including Myxococcus xanthus, which has 8 CSS, the highest number reported to date. This is the first comprehensive study carrying out a comparative analysis of the 22 available myxobacterial genomes, which suggests the evolutionary diversity of these systems. We are interested in understanding the distribution of CSS within all known myxobacteria and their probable evolution.
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24
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Pogue CB, Zhou T, Nan B. PlpA, a PilZ-like protein, regulates directed motility of the bacterium Myxococcus xanthus. Mol Microbiol 2017; 107:214-228. [PMID: 29127741 DOI: 10.1111/mmi.13878] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2017] [Indexed: 12/28/2022]
Abstract
The rod-shaped bacterium Myxococcus xanthus moves on surfaces along its long cell axis and reverses its moving direction regularly. Current models propose that the asymmetric localization of a Ras-like GTPase, MglA, to leading cell poles determines the moving direction of cells. However, cells are still motile in the mutants where MglA localizes symmetrically, suggesting the existence of additional regulators that control moving direction. In this study, we identified PlpA, a PilZ-like protein that regulates the direction of motility. PlpA and MglA localize into opposite asymmetric patterns. Deletion of the plpA gene abolishes the asymmetry of MglA localization, increases the frequency of cellular reversals and leads to severe defects in cell motility. By tracking the movements of single motor particles, we demonstrated that PlpA and MglA co-regulated the direction of gliding motility through direct interactions with the gliding motor. PlpA inhibits the reversal of individual gliding motors while MglA promotes motor reversal. By counteracting MglA near lagging cell poles, PlpA reinforces the polarity axis of MglA and thus stabilizes the direction of motility.
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Affiliation(s)
- Connor B Pogue
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Tianyi Zhou
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
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25
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Schumacher D, Søgaard-Andersen L. Regulation of Cell Polarity in Motility and Cell Division in Myxococcus xanthus. Annu Rev Microbiol 2017; 71:61-78. [PMID: 28525300 DOI: 10.1146/annurev-micro-102215-095415] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rod-shaped Myxococcus xanthus cells are polarized with proteins asymmetrically localizing to specific positions. This spatial organization is important for regulation of motility and cell division and changes over time. Dedicated protein modules regulate motility independent of the cell cycle, and cell division dependent on the cell cycle. For motility, a leading-lagging cell polarity is established that is inverted during cellular reversals. Establishment and inversion of this polarity are regulated hierarchically by interfacing protein modules that sort polarized motility proteins to the correct cell poles or cause their relocation between cell poles during reversals akin to a spatial toggle switch. For division, a novel self-organizing protein module that incorporates a ParA ATPase positions the FtsZ-ring at midcell. This review covers recent findings concerning the spatiotemporal regulation of motility and cell division in M. xanthus and illustrates how the study of diverse bacteria may uncover novel mechanisms involved in regulating bacterial cell polarity.
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Affiliation(s)
- Dominik Schumacher
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany;
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany;
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26
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Mercier R, Mignot T. Regulations governing the multicellular lifestyle of Myxococcus xanthus. Curr Opin Microbiol 2016; 34:104-110. [PMID: 27648756 DOI: 10.1016/j.mib.2016.08.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 08/30/2016] [Indexed: 10/21/2022]
Abstract
In living organisms, cooperative cell movements underlie the formation of differentiated tissues. In bacteria, Myxococcus xanthus uses cooperative group movements, to predate on prey and to form multicellular fruiting bodies, where the cells differentiate into dormant spores. Motility is controlled by a central signaling Che-like pathway, Frz. Single cell studies indicate Frz regulates the frequency at which cells reverse their direction of movement by transmitting signals to a molecular system that controls the spatial activity of the motility engines. This regulation is central to all Myxococcus multicellular behaviors but how Frz signaling generates ordered patterns is poorly understood. In this review, we first discuss the genetic structure of the Frz pathway and possible regulations that could explain its action during Myxococcus development.
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Affiliation(s)
- Romain Mercier
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
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27
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Kaimer C, Zusman DR. Regulation of cell reversal frequency inMyxococcus xanthusrequires the balanced activity of CheY-likedomains inFrzEandFrzZ. Mol Microbiol 2016; 100:379-95. [DOI: 10.1111/mmi.13323] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Christine Kaimer
- Department of Molecular and Cell Biology; University of California; Berkeley CA, 94720 USA
| | - David R. Zusman
- Department of Molecular and Cell Biology; University of California; Berkeley CA, 94720 USA
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28
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Staphylococcus aureus forms spreading dendrites that have characteristics of active motility. Sci Rep 2015; 5:17698. [PMID: 26680153 PMCID: PMC4683532 DOI: 10.1038/srep17698] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 11/03/2015] [Indexed: 01/28/2023] Open
Abstract
Staphylococcus aureus is historically regarded as a non-motile organism. More recently it has been shown that S. aureus can passively move across agar surfaces in a process called spreading. We re-analysed spreading motility using a modified assay and focused on observing the formation of dendrites: branching structures that emerge from the central colony. We discovered that S. aureus can spread across the surface of media in structures that we term ‘comets’, which advance outwards and precede the formation of dendrites. We observed comets in a diverse selection of S. aureus isolates and they exhibit the following behaviours: (1) They consist of phenotypically distinct cores of cells that move forward and seed other S. aureus cells behind them forming a comet ‘tail’; (2) they move when other cells in the comet tail have stopped moving; (3) the comet core is held together by a matrix of slime; and (4) the comets etch trails in the agar as they move forwards. Comets are not consistent with spreading motility or other forms of passive motility. Comet behaviour does share many similarities with a form of active motility known as gliding. Our observations therefore suggest that S. aureus is actively motile under certain conditions.
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29
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MglC, a Paralog of Myxococcus xanthus GTPase-Activating Protein MglB, Plays a Divergent Role in Motility Regulation. J Bacteriol 2015; 198:510-20. [PMID: 26574508 PMCID: PMC4719450 DOI: 10.1128/jb.00548-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/05/2015] [Indexed: 01/01/2023] Open
Abstract
In order to optimize interactions with their environment and one another, bacteria regulate their motility. In the case of the rod-shaped cells of Myxococcus xanthus, regulated motility is essential for social behaviors. M. xanthus moves over surfaces using type IV pilus-dependent motility and gliding motility. These two motility systems are coordinated by a protein module that controls cell polarity and consists of three polarly localized proteins, the small G protein MglA, the cognate MglA GTPase-activating protein MglB, and the response regulator RomR. Cellular reversals are induced by the Frz chemosensory system, and the output response regulator of this system, FrzZ, interfaces with the MglA/MglB/RomR module to invert cell polarity. Using a computational approach, we identify a paralog of MglB, MXAN_5770 (MglC). Genetic epistasis experiments demonstrate that MglC functions in the same pathway as MglA, MglB, RomR, and FrzZ and is important for regulating cellular reversals. Like MglB, MglC localizes to the cell poles asymmetrically and with a large cluster at the lagging pole. Correct polar localization of MglC depends on RomR and MglB. Consistently, MglC interacts directly with MglB and the C-terminal output domain of RomR, and we identified a surface of MglC that is necessary for the interaction with MglB and for MglC function. Together, our findings identify an additional member of the M. xanthus polarity module involved in regulating motility and demonstrate how gene duplication followed by functional divergence can add a layer of control to the complex cellular processes of motility and motility regulation.
IMPORTANCE Gene duplication and the subsequent divergence of the duplicated genes are important evolutionary mechanisms for increasing both biological complexity and regulation of biological processes. The bacterium Myxococcus xanthus is a soil bacterium with an unusually large genome that carries out several social processes, including predation of other bacterial species and formation of multicellular, spore-filled fruiting bodies. One feature of the large M. xanthus genome is that it contains many gene duplications. Here, we compare the products of one example of gene duplication and divergence, in which a paralog of the cognate MglA GTPase-activating protein MglB has acquired a different and opposing role in the regulation of cellular polarity and motility, processes critical to the bacterium's social behaviors.
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Islam ST, Mignot T. The mysterious nature of bacterial surface (gliding) motility: A focal adhesion-based mechanism in Myxococcus xanthus. Semin Cell Dev Biol 2015; 46:143-54. [PMID: 26520023 DOI: 10.1016/j.semcdb.2015.10.033] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/26/2015] [Accepted: 10/26/2015] [Indexed: 11/19/2022]
Abstract
Motility of bacterial cells promotes a range of important physiological phenomena such as nutrient detection, harm avoidance, biofilm formation, and pathogenesis. While much research has been devoted to the mechanism of bacterial swimming in liquid via rotation of flagellar filaments, the mechanisms of bacterial translocation across solid surfaces are poorly understood, particularly when cells lack external appendages such as rotary flagella and/or retractile type IV pili. Under such limitations, diverse bacteria at the single-cell level are still able to "glide" across solid surfaces, exhibiting smooth translocation of the cell along its long axis. Though multiple gliding mechanisms have evolved in different bacterial classes, most remain poorly characterized. One exception is the gliding motility mechanism used by the Gram-negative social predatory bacterium Myxococcus xanthus. The available body of research suggests that M. xanthus gliding motility is mediated by trafficked multi-protein (Glt) cell envelope complexes, powered by proton-driven flagellar stator homologues (Agl). Through coupling to the substratum via polysaccharide slime, Agl-Glt assemblies can become fixed relative to the substratum, forming a focal adhesion site. Continued directional transport of slime-associated substratum-fixed Agl-Glt complexes would result in smooth forward movement of the cell. In this review, we have provided a comprehensive synthesis of the latest mechanistic and structural data for focal adhesion-mediated gliding motility in M. xanthus, with emphasis on the role of each Agl and Glt protein. Finally, we have also highlighted the possible connection between the motility complex and a new type of spore coat assembly system, suggesting that gliding and cell envelope synthetic complexes are evolutionarily linked.
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Affiliation(s)
- Salim T Islam
- Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique (CNRS) UMR7283, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 chemin Joseph Aiguier, 13009 Marseille, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique (CNRS) UMR7283, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 chemin Joseph Aiguier, 13009 Marseille, France.
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Chen JC, Liu JH, Hsu DW, Shu JC, Chen CY, Chen CC. Methylatable Signaling Helix Coordinated Inhibitory Receiver Domain in Sensor Kinase Modulates Environmental Stress Response in Bacillus Cereus. PLoS One 2015; 10:e0137952. [PMID: 26379238 PMCID: PMC4574943 DOI: 10.1371/journal.pone.0137952] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/25/2015] [Indexed: 02/08/2023] Open
Abstract
σB, an alternative transcription factor, controls the response of the cell to a variety of environmental stresses in Bacillus cereus. Previously, we reported that RsbM negatively regulates σB through the methylation of RsbK, a hybrid sensor kinase, on a signaling helix (S-helix). However, RsbK comprises a C-terminal receiver (REC) domain whose function remains unclear. In this study, deletion of the C-terminal REC domain of RsbK resulted in high constitutive σB expression independent of environmental stimuli. Thus, the REC domain may serve as an inhibitory element. Mutagenic substitution was employed to modify the putative phospho-acceptor residue D827 in the REC domain of RsbK. The expression of RsbKD827N and RsbKD827E exhibited high constitutive σB, indicating that D827, if phosphorylatable, possibly participates in σB regulation. Bacterial two-hybrid analyses demonstrated that RsbK forms a homodimer and the REC domain interacts mainly with the histidine kinase (HK) domain and partly with the S-helix. In particular, co-expression of RsbM strengthens the interaction between the REC domain and the S-helix. Consistently, our structural model predicts a significant interaction between the HK and REC domains of the RsbK intradimer. Here, we demonstrated that coordinated the methylatable S-helix and the REC domain of RsbK is functionally required to modulate σB-mediated stress response in B. cereus and maybe ubiquitous in microorganisms encoded RsbK-type sensor kinases.
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Affiliation(s)
- Jung-Chi Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Jyung-Hurng Liu
- Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung, Taiwan
- Agricultural Biotechnology Center (ABC), National Chung Hsing University, Taichung, Taiwan
| | - Duen-Wei Hsu
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
| | - Jwu-Ching Shu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Tao-Yuan, Taiwan
| | - Chien-Yen Chen
- Department of Earth and Environmental Sciences, National Chung Cheng University, Chiayi, Taiwan
| | - Chien-Cheng Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, Taiwan
- * E-mail:
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Guzzo M, Agrebi R, Espinosa L, Baronian G, Molle V, Mauriello EMF, Brochier-Armanet C, Mignot T. Evolution and Design Governing Signal Precision and Amplification in a Bacterial Chemosensory Pathway. PLoS Genet 2015; 11:e1005460. [PMID: 26291327 PMCID: PMC4546325 DOI: 10.1371/journal.pgen.1005460] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/23/2015] [Indexed: 11/19/2022] Open
Abstract
Understanding the principles underlying the plasticity of signal transduction networks is fundamental to decipher the functioning of living cells. In Myxococcus xanthus, a particular chemosensory system (Frz) coordinates the activity of two separate motility systems (the A- and S-motility systems), promoting multicellular development. This unusual structure asks how signal is transduced in a branched signal transduction pathway. Using combined evolution-guided and single cell approaches, we successfully uncoupled the regulations and showed that the A-motility regulation system branched-off an existing signaling system that initially only controlled S-motility. Pathway branching emerged in part following a gene duplication event and changes in the circuit structure increasing the signaling efficiency. In the evolved pathway, the Frz histidine kinase generates a steep biphasic response to increasing external stimulations, which is essential for signal partitioning to the motility systems. We further show that this behavior results from the action of two accessory response regulator proteins that act independently to filter and amplify signals from the upstream kinase. Thus, signal amplification loops may underlie the emergence of new connectivity in signal transduction pathways.
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Affiliation(s)
- Mathilde Guzzo
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS Aix-Marseille University UMR 7283, Marseille, France
| | - Rym Agrebi
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS Aix-Marseille University UMR 7283, Marseille, France
| | - Leon Espinosa
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS Aix-Marseille University UMR 7283, Marseille, France
| | - Grégory Baronian
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, CNRS Universités de Montpellier II et I, UMR 5235, case 107, Montpellier, France
| | - Virginie Molle
- Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, CNRS Universités de Montpellier II et I, UMR 5235, case 107, Montpellier, France
| | - Emilia M. F. Mauriello
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS Aix-Marseille University UMR 7283, Marseille, France
| | - Céline Brochier-Armanet
- Université de Lyon, Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS Aix-Marseille University UMR 7283, Marseille, France
- * E-mail:
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Treuner-Lange A, Macia E, Guzzo M, Hot E, Faure LM, Jakobczak B, Espinosa L, Alcor D, Ducret A, Keilberg D, Castaing JP, Lacas Gervais S, Franco M, Søgaard-Andersen L, Mignot T. The small G-protein MglA connects to the MreB actin cytoskeleton at bacterial focal adhesions. J Cell Biol 2015; 210:243-56. [PMID: 26169353 PMCID: PMC4508894 DOI: 10.1083/jcb.201412047] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 06/09/2015] [Indexed: 12/27/2022] Open
Abstract
In Myxococcus xanthus the gliding motility machinery is assembled at the leading cell pole to form focal adhesions, translocated rearward to propel the cell, and disassembled at the lagging pole. We show that MglA, a Ras-like small G-protein, is an integral part of this machinery. In this function, MglA stimulates the assembly of the motility complex by directly connecting it to the MreB actin cytoskeleton. Because the nucleotide state of MglA is regulated spatially and MglA only binds MreB in the guanosine triphosphate-bound form, the motility complexes are assembled at the leading pole and dispersed at the lagging pole where the guanosine triphosphatase activating protein MglB disrupts the MglA-MreB interaction. Thus, MglA acts as a nucleotide-dependent molecular switch to regulate the motility machinery spatially. The function of MreB in motility is independent of its function in peptidoglycan synthesis, representing a coopted function. Our findings highlight a new function for the MreB cytoskeleton and suggest that G-protein-cytoskeleton interactions are a universally conserved feature.
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Affiliation(s)
- Anke Treuner-Lange
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Eric Macia
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275 Centre National de la Recherche Scientifique, Université de Nice Sophia Antipolis, 06560 Valbonne, France
| | - Mathilde Guzzo
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
| | - Edina Hot
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Laura M Faure
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
| | - Beata Jakobczak
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Leon Espinosa
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
| | - Damien Alcor
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275 Centre National de la Recherche Scientifique, Université de Nice Sophia Antipolis, 06560 Valbonne, France
| | - Adrien Ducret
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
| | - Daniela Keilberg
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Jean Philippe Castaing
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
| | - Sandra Lacas Gervais
- Centre Commun de Microscopie Appliquée, Université de Nice Sophia Antipolis, 06103 Nice, France
| | - Michel Franco
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275 Centre National de la Recherche Scientifique, Université de Nice Sophia Antipolis, 06560 Valbonne, France
| | | | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, UMR 7283 Centre National de la Recherche Scientifique, Aix Marseille University, 13009 Marseille, France
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Jakobczak B, Keilberg D, Wuichet K, Søgaard-Andersen L. Contact- and Protein Transfer-Dependent Stimulation of Assembly of the Gliding Motility Machinery in Myxococcus xanthus. PLoS Genet 2015; 11:e1005341. [PMID: 26132848 PMCID: PMC4488436 DOI: 10.1371/journal.pgen.1005341] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 06/08/2015] [Indexed: 01/06/2023] Open
Abstract
Bacteria engage in contact-dependent activities to coordinate cellular activities that aid their survival. Cells of Myxococcus xanthus move over surfaces by means of type IV pili and gliding motility. Upon direct contact, cells physically exchange outer membrane (OM) lipoproteins, and this transfer can rescue motility in mutants lacking lipoproteins required for motility. The mechanism of gliding motility and its stimulation by transferred OM lipoproteins remain poorly characterized. We investigated the function of CglC, GltB, GltA and GltC, all of which are required for gliding. We demonstrate that CglC is an OM lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB and GltA are mutually stabilizing, and both are required to stabilize GltC, whereas CglC accumulate independently of GltB, GltA and GltC. Consistently, purified GltB, GltA and GltC proteins interact in all pair-wise combinations. Using active fluorescently-tagged fusion proteins, we demonstrate that GltB, GltA and GltC are integral components of the gliding motility complex. Incorporation of GltB and GltA into this complex depends on CglC and GltC as well as on the cytoplasmic AglZ protein and the inner membrane protein AglQ, both of which are components of the gliding motility complex. Conversely, incorporation of AglZ and AglQ into the gliding motility complex depends on CglC, GltB, GltA and GltC. Remarkably, physical transfer of the OM lipoprotein CglC to a ΔcglC recipient stimulates assembly of the gliding motility complex in the recipient likely by facilitating the OM integration of GltB and GltA. These data provide evidence that the gliding motility complex in M. xanthus includes OM proteins and suggest that this complex extends from the cytoplasm across the cell envelope to the OM. These data add assembly of gliding motility complexes in M. xanthus to the growing list of contact-dependent activities in bacteria. Motility facilitates a wide variety of processes such as virulence, biofilm formation and development in bacteria. Bacteria have evolved at least three mechanisms for motility on surfaces: swarming motility, twitching motility and gliding motility. Mechanistically, gliding motility is poorly understood. Here, we focused on four proteins in Myxococcus xanthus that are essential for gliding. We show that CglC is an outer membrane (OM) lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB, GltA and GltC are components of the gliding motility complex, and CglC likely stimulates the integration of GltB and GltA into the OM. Moreover, CglC, in a cell-cell contact-dependent manner, can be transferred from a cglC+ donor to a ΔcglC mutant leading to stimulation of gliding motility in the recipient. We show that upon physical transfer of CglC, CglC stimulates the assembly of the gliding motility complex in the recipient. The data presented here adds to the growing list of cell-cell contact-dependent activities in bacteria by demonstrating that gliding motility can be stimulated in a contact-dependent manner by transfer of a protein that stimulates assembly of the gliding motility complexes.
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Affiliation(s)
- Beata Jakobczak
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Daniela Keilberg
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Kristin Wuichet
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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Leighton TL, Buensuceso RNC, Howell PL, Burrows LL. Biogenesis of Pseudomonas aeruginosa type IV pili and regulation of their function. Environ Microbiol 2015; 17:4148-63. [PMID: 25808785 DOI: 10.1111/1462-2920.12849] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 03/13/2015] [Accepted: 03/14/2015] [Indexed: 12/27/2022]
Abstract
Type IV pili (T4P) are bacterial virulence factors involved in a wide variety of functions including deoxyribonucleic acid uptake, surface attachment, biofilm formation and twitching motility. While T4P are common surface appendages, the systems that assemble them and the regulation of their function differ between species. Pseudomonas aeruginosa, Neisseria spp. and Myxococcus xanthus are common model systems used to study T4P biology. This review focuses on recent advances in P. aeruginosa T4P structural biology, and the regulatory pathways controlling T4P biogenesis and function.
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Affiliation(s)
- Tiffany L Leighton
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Ryan N C Buensuceso
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - P Lynne Howell
- Program in Molecular Structure & Function, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
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Arginine-rhamnosylation as new strategy to activate translation elongation factor P. Nat Chem Biol 2015; 11:266-70. [PMID: 25686373 DOI: 10.1038/nchembio.1751] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/22/2014] [Indexed: 12/26/2022]
Abstract
Ribosome stalling at polyproline stretches is common and fundamental. In bacteria, translation elongation factor P (EF-P) rescues such stalled ribosomes, but only when it is post-translationally activated. In Escherichia coli, activation of EF-P is achieved by (R)-β-lysinylation and hydroxylation of a conserved lysine. Here we have unveiled a markedly different modification strategy in which a conserved arginine of EF-P is rhamnosylated by a glycosyltransferase (EarP) using dTDP-L-rhamnose as a substrate. This is to our knowledge the first report of N-linked protein glycosylation on arginine in bacteria and the first example in which a glycosylated side chain of a translation elongation factor is essential for function. Arginine-rhamnosylation of EF-P also occurs in clinically relevant bacteria such as Pseudomonas aeruginosa. We demonstrate that the modification is needed to develop pathogenicity, making EarP and dTDP-L-rhamnose-biosynthesizing enzymes ideal targets for antibiotic development.
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The polarity of myxobacterial gliding is regulated by direct interactions between the gliding motors and the Ras homolog MglA. Proc Natl Acad Sci U S A 2014; 112:E186-93. [PMID: 25550521 DOI: 10.1073/pnas.1421073112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gliding motility in Myxococcus xanthus is powered by flagella stator homologs that move in helical trajectories using proton motive force. The Frz chemosensory pathway regulates the cell polarity axis through MglA, a Ras family GTPase; however, little is known about how MglA establishes the polarity of gliding, because the gliding motors move simultaneously in opposite directions. Here we examined the localization and dynamics of MglA and gliding motors in high spatial and time resolution. We determined that MglA localizes not only at the cell poles, but also along the cell bodies, forming a decreasing concentration gradient toward the lagging cell pole. MglA directly interacts with the motor protein AglR, and the spatial distribution of AglR reversals is positively correlated with the MglA gradient. Thus, the motors moving toward lagging cell poles are less likely to reverse, generating stronger forward propulsion. MglB, the GTPase-activating protein of MglA, regulates motor reversal by maintaining the MglA gradient. Our results suggest a mechanism whereby bacteria use Ras family proteins to modulate cellular polarity.
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Wuichet K, Søgaard-Andersen L. Evolution and diversity of the Ras superfamily of small GTPases in prokaryotes. Genome Biol Evol 2014; 7:57-70. [PMID: 25480683 PMCID: PMC4316618 DOI: 10.1093/gbe/evu264] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ras superfamily of small GTPases are single domain nucleotide-dependent molecular switches that act as highly tuned regulators of complex signal transduction pathways. Originally identified in eukaryotes for their roles in fundamental cellular processes including proliferation, motility, polarity, nuclear transport, and vesicle transport, recent studies have revealed that single domain GTPases also control complex functions such as cell polarity, motility, predation, development and antibiotic resistance in bacteria. Here, we used a computational genomics approach to understand the abundance, diversity, and evolution of small GTPases in prokaryotes. We collected 520 small GTPase sequences present in 17% of 1,611 prokaryotic genomes analyzed that cover diverse lineages. We identified two discrete families of small GTPases in prokaryotes that show evidence of three distinct catalytic mechanisms. The MglA family includes MglA homologs, which are typically associated with the MglB GTPase activating protein, whereas members of the Rup (Ras superfamily GTPase of unknown function in prokaryotes) family are not predicted to interact with MglB homologs. System classification and genome context analyses support the involvement of small GTPases in diverse prokaryotic signal transduction pathways including two component systems, laying the foundation for future experimental characterization of these proteins. Phylogenetic analysis of prokaryotic and eukaryotic GTPases supports that the last universal common ancestor contained ancestral MglA and Rup family members. We propose that the MglA family was lost from the ancestral eukaryote and that the Ras superfamily members in extant eukaryotes are the result of vertical and horizontal gene transfer events of ancestral Rup GTPases.
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Affiliation(s)
- Kristin Wuichet
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
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Salzer R, Joos F, Averhoff B. Different effects of MglA and MglB on pilus-mediated functions and natural competence in Thermus thermophilus. Extremophiles 2014; 19:261-7. [PMID: 25472010 DOI: 10.1007/s00792-014-0711-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/16/2014] [Indexed: 02/02/2023]
Abstract
The thermophilic bacterium Thermus thermophilus is known for its high natural competence. Uptake of DNA is mediated by a DNA translocator that shares components with type IV pili. Localization and function of type IV pili in other bacteria depend on the cellular localization at the poles of the bacterium, a process that involves MglA and MglB. T. thermophilus contains homologs of MglA and MglB. The genes encoding MglA and MglB were deleted and the physiology of the mutants was studied. Deletion of the genes individually or in tandem had no effect on pili formation but pili lost their localization at the poles. The mutants abolished pilus-mediated functions such as twitching motility and adherence but had no effect on uptake of DNA by natural competence. These data demonstrate that MglA and MglB are dispensable for natural transformation and are consistent with the hypothesis that uptake of DNA does not depend on type IV pili or their cellular localization.
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Affiliation(s)
- Ralf Salzer
- Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt am Main, Germany
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Rashkov P, Schmitt BA, Keilberg D, Beck K, Søgaard-Andersen L, Dahlke S. A model for spatio-temporal dynamics in a regulatory network for cell polarity. Math Biosci 2014; 258:189-200. [PMID: 25445576 DOI: 10.1016/j.mbs.2014.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 10/17/2014] [Accepted: 10/21/2014] [Indexed: 10/24/2022]
Abstract
Cell polarity in Myxococcus xanthus is crucial for the directed motility of individual cells. The polarity system is characterised by a dynamic spatio-temporal localisation of the regulatory proteins MglA and MglB at opposite cell poles. In response to signalling by the Frz chemosensory system, MglA and MglB are released from the poles and then rebind at the opposite poles. Thus, over time MglA and MglB oscillate irregularly between the poles in synchrony but out of phase. A minimal macroscopic model of the Mgl/Frz regulatory system based on a reaction-diffusion PDE system is presented. Mathematical analysis of the steady states derives conditions on the reaction terms for formation of dynamic localisation patterns of the regulatory proteins under different biologically-relevant regimes, i.e. with and without Frz signalling. Numerical simulations of the model system produce either a stationary pattern in time (fixed polarity), periodic solutions in time (oscillating polarity), or excitable behaviour (irregular switching of polarity).
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Affiliation(s)
- Peter Rashkov
- Department of Mathematics and Informatics, Philipps-Universität Marburg, Hans-Meerwein-Str., 35032 Marburg, Germany.
| | - Bernhard A Schmitt
- Department of Mathematics and Informatics, Philipps-Universität Marburg, Hans-Meerwein-Str., 35032 Marburg, Germany
| | - Daniela Keilberg
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | | | - Lotte Søgaard-Andersen
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany
| | - Stephan Dahlke
- Department of Mathematics and Informatics, Philipps-Universität Marburg, Hans-Meerwein-Str., 35032 Marburg, Germany
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Eckhert E, Rangamani P, Davis AE, Oster G, Berleman JE. Dual biochemical oscillators may control cellular reversals in Myxococcus xanthus. Biophys J 2014; 107:2700-11. [PMID: 25468349 DOI: 10.1016/j.bpj.2014.09.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/22/2014] [Accepted: 09/25/2014] [Indexed: 10/24/2022] Open
Abstract
Myxococcus xanthus is a Gram-negative, soil-dwelling bacterium that glides on surfaces, reversing direction approximately once every 6 min. Motility in M. xanthus is governed by the Che-like Frz pathway and the Ras-like Mgl pathway, which together cause the cell to oscillate back and forth. Previously, Igoshin et al. (2004) suggested that the cellular oscillations are caused by cyclic changes in concentration of active Frz proteins that govern motility. In this study, we present a computational model that integrates both the Frz and Mgl pathways, and whose downstream components can be read as motor activity governing cellular reversals. This model faithfully reproduces wildtype and mutant behaviors by simulating individual protein knockouts. In addition, the model can be used to examine the impact of contact stimuli on cellular reversals. The basic model construction relies on the presence of two nested feedback circuits, which prompted us to reexamine the behavior of M. xanthus cells. We performed experiments to test the model, and this cell analysis challenges previous assumptions of 30 to 60 min reversal periods in frzCD, frzF, frzE, and frzZ mutants. We demonstrate that this average reversal period is an artifact of the method employed to record reversal data, and that in the absence of signal from the Frz pathway, Mgl components can occasionally reverse the cell near wildtype periodicity, but frz- cells are otherwise in a long nonoscillating state.
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Affiliation(s)
- Erik Eckhert
- University of California, Berkeley/University of California, San Francisco Joint Medical Program, Berkeley, California; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California
| | - Annie E Davis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California
| | - George Oster
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California
| | - James E Berleman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California; Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California; Department of Biology, St. Mary's College, Moraga, California.
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Abstract
Bacteria are polarized cells with many asymmetrically localized proteins that are regulated temporally and spatially. This spatiotemporal dynamics is critical for several fundamental cellular processes including growth, division, cell cycle regulation, chromosome segregation, differentiation, and motility. Therefore, understanding how proteins find their correct location at the right time is crucial for elucidating bacterial cell function. Despite the diversity of proteins displaying spatiotemporal dynamics, general principles for the dynamic regulation of protein localization to the cell poles and the midcell are emerging. These principles include diffusion-capture, self-assembling polymer-forming landmark proteins, nonpolymer forming landmark proteins, matrix-dependent self-organizing ParA/MinD ATPases, and small Ras-like GTPases.
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Affiliation(s)
- Anke Treuner-Lange
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
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Cell division resets polarity and motility for the bacterium Myxococcus xanthus. J Bacteriol 2014; 196:3853-61. [PMID: 25157084 DOI: 10.1128/jb.02095-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Links between cell division and other cellular processes are poorly understood. It is difficult to simultaneously examine division and function in most cell types. Most of the research probing aspects of cell division has experimented with stationary or immobilized cells or distinctly asymmetrical cells. Here we took an alternative approach by examining cell division events within motile groups of cells growing on solid medium by time-lapse microscopy. A total of 558 cell divisions were identified among approximately 12,000 cells. We found an interconnection of division, motility, and polarity in the bacterium Myxococcus xanthus. For every division event, motile cells stop moving to divide. Progeny cells of binary fission subsequently move in opposing directions. This behavior involves M. xanthus Frz proteins that regulate M. xanthus motility reversals but is independent of type IV pilus "S motility." The inheritance of opposing polarity is correlated with the distribution of the G protein RomR within these dividing cells. The constriction at the point of division limits the intracellular distribution of RomR. Thus, the asymmetric distribution of RomR at the parent cell poles becomes mirrored at new poles initiated at the site of division.
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Milner DS, Till R, Cadby I, Lovering AL, Basford SM, Saxon EB, Liddell S, Williams LE, Sockett RE. Ras GTPase-like protein MglA, a controller of bacterial social-motility in Myxobacteria, has evolved to control bacterial predation by Bdellovibrio. PLoS Genet 2014; 10:e1004253. [PMID: 24721965 PMCID: PMC3983030 DOI: 10.1371/journal.pgen.1004253] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 02/04/2014] [Indexed: 12/18/2022] Open
Abstract
Bdellovibrio bacteriovorus invade Gram-negative bacteria in a predatory process requiring Type IV pili (T4P) at a single invasive pole, and also glide on surfaces to locate prey. Ras-like G-protein MglA, working with MglB and RomR in the deltaproteobacterium Myxococcus xanthus, regulates adventurous gliding and T4P-mediated social motility at both M. xanthus cell poles. Our bioinformatic analyses suggested that the GTPase activating protein (GAP)-encoding gene mglB was lost in Bdellovibrio, but critical residues for MglABd GTP-binding are conserved. Deletion of mglABd abolished prey-invasion, but not gliding, and reduced T4P formation. MglABd interacted with a previously uncharacterised tetratricopeptide repeat (TPR) domain protein Bd2492, which we show localises at the single invasive pole and is required for predation. Bd2492 and RomR also interacted with cyclic-di-GMP-binding receptor CdgA, required for rapid prey-invasion. Bd2492, RomRBd and CdgA localize to the invasive pole and may facilitate MglA-docking. Bd2492 was encoded from an operon encoding a TamAB-like secretion system. The TamA protein and RomR were found, by gene deletion tests, to be essential for viability in both predatory and non-predatory modes. Control proteins, which regulate bipolar T4P-mediated social motility in swarming groups of deltaproteobacteria, have adapted in evolution to regulate the anti-social process of unipolar prey-invasion in the “lone-hunter” Bdellovibrio. Thus GTP-binding proteins and cyclic-di-GMP inputs combine at a regulatory hub, turning on prey-invasion and allowing invasion and killing of bacterial pathogens and consequent predatory growth of Bdellovibrio. Bacterial cell polarity control is important for maintaining asymmetry of polar components such as flagella and pili. Bdellovibrio bacteriovorus is a predatory deltaproteobacterium which attaches to, and invades, other bacteria using Type IV pili (T4P) extruded from the specialised, invasive, non-flagellar pole of the cell. It was not known how that invasive pole is specified and regulated. Here we discover that a regulatory protein-hub, including Ras-GTPase-like protein MglA and cyclic-di-GMP receptor-protein CdgA, control prey-invasion. In the deltaproteobacterium, Myxococcus xanthus, MglA, with MglB and RomR, was found by others to regulate switching of T4P in social ‘swarming’ surface motility by swapping the pole at which T4P are found. In contrast, in B. bacteriovorus MglA regulates the process of prey-invasion and RomR, which is required for surface motility regulation in Myxococcus, is essential for growth and viability in Bdellovibrio. During evolution, B. bacteriovorus has lost mglB, possibly as T4P-pole-switching is not required; pili are only required at the invasive pole. A previously unidentified tetratricopeptide repeat (TPR) protein interacts with MglA and is essential for prey-invasion. This regulatory protein hub allows prey-invasion, likely integrating cyclic-di-GMP signals, pilus assembly and TamAB secretion in B. bacteriovorus.
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Affiliation(s)
- David S. Milner
- Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Rob Till
- Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Ian Cadby
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew L. Lovering
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Sarah M. Basford
- Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Emma B. Saxon
- Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
| | - Susan Liddell
- School of Biosciences, University of Nottingham, Sutton Bonington, Nottinghamshire, United Kingdom
| | - Laura E. Williams
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
| | - R. Elizabeth Sockett
- Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom
- * E-mail:
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Keilberg D, Søgaard-Andersen L. Regulation of bacterial cell polarity by small GTPases. Biochemistry 2014; 53:1899-907. [PMID: 24655121 DOI: 10.1021/bi500141f] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bacteria are polarized with many proteins localizing dynamically to specific subcellular sites. Two GTPase families have important functions in the regulation of bacterial cell polarity, FlhF homologues and small GTPases of the Ras superfamily. The latter consist of only a G domain and are widespread in bacteria. The rod-shaped Myxococcus xanthus cells have two motility systems, one for gliding and one that depends on type IV pili. The function of both systems hinges on proteins that localize asymmetrically to the cell poles. During cellular reversals, these asymmetrically localized proteins are released from their respective poles and then bind to the opposite pole, resulting in an inversion of cell polarity. Here, we review genetic, cell biological, and biochemical analyses that identified two modules containing small Ras-like GTPases that regulate the dynamic polarity of motility proteins. The GTPase SofG interacts directly with the bactofilin cytoskeletal protein BacP to ensure polar localization of type IV pili proteins. In the second module, the small GTPase MglA, its cognate GTPase activating protein (GAP) MglB, and the response regulator RomR localize asymmetrically to the poles and sort dynamically localized motility proteins to the poles. During reversals, MglA, MglB, and RomR switch poles, in that way inducing the relocation of dynamically localized motility proteins. Structural analyses have demonstrated that MglB has a Roadblock/LC7 fold, the central β2 strand in MglA undergoes an unusual screw-type movement upon GTP binding, MglA contains an intrinsic Arg finger required for GTP hydrolysis, and MglA and MglB form an unusual G protein/GAP complex with a 1:2 stoichiometry.
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Affiliation(s)
- Daniela Keilberg
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology , Karl-von-Frisch Strasse 10, 35043 Marburg, Germany
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Josenhans C, Jung K, Rao CV, Wolfe AJ. A tale of two machines: a review of the BLAST meeting, Tucson, AZ, 20-24 January 2013. Mol Microbiol 2013; 91:6-25. [PMID: 24125587 DOI: 10.1111/mmi.12427] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2013] [Indexed: 01/06/2023]
Abstract
Since its inception, Bacterial Locomotion and Signal Transduction (BLAST) meetings have been the place to exchange and share the latest developments in the field of bacterial signal transduction and motility. At the 12th BLAST meeting, held last January in Tucson, AZ, researchers from all over the world met to report and discuss progress in diverse aspects of the field. The majority of these advances, however, came at the level of atomic level structures and their associated mechanisms. This was especially true of the biological machines that sense and respond to environmental changes.
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Affiliation(s)
- Christine Josenhans
- Institute for Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Carl-Neuberg Strasse 1, 30625, Hannover, Germany
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47
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Davis BM, Waldor MK. Establishing polar identity in gram-negative rods. Curr Opin Microbiol 2013; 16:752-9. [PMID: 24029491 DOI: 10.1016/j.mib.2013.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/05/2013] [Accepted: 08/17/2013] [Indexed: 11/30/2022]
Abstract
In rod shaped bacteria, numerous cellular components are targeted to the cell poles, and such localization is often important for optimal function. In particular, recognition of poles is often linked to division site selection, chromosome segregation, chemotactic signaling, and motility. Recent advances in understanding polarity include identification of a Vibrio cholerae protein that mediates polar localization of a chromosome origin and chemotaxis clusters, as well as a downstream protein that contributes solely to localization of chemotaxis proteins. In Caulobacter crescentus, the molecular mechanisms by which polar determinants and effectors are localized, and the key roles for nucleotide-dependent switches, have been defined. Finally, roles for, and interactions between, factors that mediate environmentally determined polarity in Myxococcus xanthus have recently been characterized.
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Affiliation(s)
- Brigid M Davis
- Division of Infectious Diseases, Brigham & Women's Hospital and Department of Microbiology and Immunology, Harvard Medical School and HHMI, United States.
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48
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Kaimer C, Zusman DR. Phosphorylation-dependent localization of the response regulator FrzZ signals cell reversals in Myxococcus xanthus. Mol Microbiol 2013; 88:740-53. [PMID: 23551551 DOI: 10.1111/mmi.12219] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2013] [Indexed: 12/21/2022]
Abstract
The life cycle of Myxococcus xanthus includes co-ordinated group movement and fruiting body formation, and requires directed motility and controlled cell reversals. Reversals are achieved by inverting cell polarity and re-organizing many motility proteins. The Frz chemosensory pathway regulates the frequency of cell reversals. While it has been established that phosphotransfer from the kinase FrzE to the response regulator FrzZ is required, it is unknown how phosphorylated FrzZ, the putative output of the pathway, targets the cell polarity axis. In this study, we used Phos-tag SDS-PAGE to determine the cellular level of phospho-FrzZ under different growth conditions and in Frz signalling mutants. We detected consistent FrzZ phosphorylation, albeit with a short half-life, in cells grown on plates, but not from liquid culture. The available pool of phospho-FrzZ correlated with reversal frequencies, with higher levels found in hyper-reversing mutants. Phosphorylation was not detected in hypo-reversing mutants. Fluorescence microscopy revealed that FrzZ is recruited to the leading cell pole upon phosphorylation and switches to the opposite pole during reversals. These results are consistent with the hypothesis that the Frz pathway modulates reversal frequency through a localized response regulator that targets cell polarity regulators at the leading cell pole.
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Affiliation(s)
- Christine Kaimer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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49
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Two Small GTPases Act in Concert with the Bactofilin Cytoskeleton to Regulate Dynamic Bacterial Cell Polarity. Dev Cell 2013; 25:119-31. [DOI: 10.1016/j.devcel.2013.02.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 02/11/2013] [Accepted: 02/26/2013] [Indexed: 11/30/2022]
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50
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Kaimer C, Berleman JE, Zusman DR. Chemosensory signaling controls motility and subcellular polarity in Myxococcus xanthus. Curr Opin Microbiol 2012; 15:751-7. [PMID: 23142584 DOI: 10.1016/j.mib.2012.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 09/28/2012] [Accepted: 10/15/2012] [Indexed: 01/04/2023]
Abstract
Myxococcus xanthus is a model system for the study of dynamic protein localization and cell polarity in bacteria. M. xanthus cells are motile on solid surfaces enabled by two forms of motility. Motility is controlled by the Che-like Frz pathway, which is essential for fruiting body formation and differentiation. The Frz signal is mediated by a GTPase/GAP protein pair that establishes cell polarity and directs the motility systems. Pilus driven motility at the leading pole of the cell requires dynamic localization of two ATPases and the coordinated production of EPS synthesis. Gliding motility requires dynamic movement of large protein complexes, but the mechanism by which this system generates propulsive force is still an active area of investigation.
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Affiliation(s)
- Christine Kaimer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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