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Chakraborty S, Kanade M, Gayathri P. Mechanism of GTPase activation of a prokaryotic small Ras-like GTPase MglA by an asymmetrically interacting MglB dimer. J Biol Chem 2024; 300:107197. [PMID: 38508314 PMCID: PMC11016934 DOI: 10.1016/j.jbc.2024.107197] [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: 02/03/2024] [Accepted: 03/04/2024] [Indexed: 03/22/2024] Open
Abstract
Cell polarity oscillations in Myxococcus xanthus motility are driven by a prokaryotic small Ras-like GTPase, mutual gliding protein A (MglA), which switches from one cell pole to the other in response to extracellular signals. MglA dynamics is regulated by MglB, which functions both as a GTPase activating protein (GAP) and a guanine nucleotide exchange factor (GEF) for MglA. With an aim to dissect the asymmetric role of the two MglB protomers in the dual GAP and GEF activities, we generated a functional MglAB complex by coexpressing MglB with a linked construct of MglA and MglB. This strategy enabled us to generate mutations of individual MglB protomers (MglB1 or MglB2 linked to MglA) and delineate their role in GEF and GAP activities. We establish that the C-terminal helix of MglB1, but not MglB2, stimulates nucleotide exchange through a site away from the nucleotide-binding pocket, confirming an allosteric mechanism. Interaction between the N-terminal β-strand of MglB1 and β0 of MglA is essential for the optimal GEF activity of MglB. Specific residues of MglB2, which interact with Switch-I of MglA, partially contribute to its GAP activity. Thus, the role of the MglB2 protomer in the GAP activity of MglB is limited to restricting the conformation of MglA active site loops. The direct demonstration of the allosteric mechanism of GEF action provides us new insights into the regulation of small Ras-like GTPases, a feature potentially present in many uncharacterized GEFs.
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Affiliation(s)
- Sukanya Chakraborty
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Manil Kanade
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Pananghat Gayathri
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India.
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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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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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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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Keane R, Berleman J. The predatory life cycle of Myxococcus xanthus. Microbiology (Reading) 2016; 162:1-11. [DOI: 10.1099/mic.0.000208] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Ryan Keane
- Department of Biology, Saint Mary's College, Moraga, CA 94556, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - James Berleman
- Department of Biology, Saint Mary's College, Moraga, CA 94556, USA
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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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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Abstract
Many bacteria glide smoothly on surfaces, despite having no discernable propulsive organelles on their surface. Recent experiments with Myxococcus xanthus and Flavobacterium johnsoniae show that both of these distantly related bacterial species glide using proteins that move in helical tracks, albeit with significantly different motility mechanisms. Both species utilize proton-motive force for movement. Although the motors that power gliding in M. xanthus have been identified, the F. johnsoniae motors remain to be discovered.
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Affiliation(s)
- Beiyan Nan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Mark J McBride
- Department of Biological Sciences, University of Wisconsin-Milwaukee, WI 53201, USA
| | - Jing Chen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David R Zusman
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - George Oster
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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