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Duart G, Graña-Montes R, Pastor-Cantizano N, Mingarro I. Experimental and computational approaches for membrane protein insertion and topology determination. Methods 2024; 226:102-119. [PMID: 38604415 DOI: 10.1016/j.ymeth.2024.03.012] [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: 11/07/2023] [Revised: 03/13/2024] [Accepted: 03/22/2024] [Indexed: 04/13/2024] Open
Abstract
Membrane proteins play pivotal roles in a wide array of cellular processes and constitute approximately a quarter of the protein-coding genes across all organisms. Despite their ubiquity and biological significance, our understanding of these proteins remains notably less comprehensive compared to their soluble counterparts. This disparity in knowledge can be attributed, in part, to the inherent challenges associated with employing specialized techniques for the investigation of membrane protein insertion and topology. This review will center on a discussion of molecular biology methodologies and computational prediction tools designed to elucidate the insertion and topology of helical membrane proteins.
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Affiliation(s)
- Gerard Duart
- Departament de Bioquímica i Biologia Molecular, Institut Universitari de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain
| | - Ricardo Graña-Montes
- Departament de Bioquímica i Biologia Molecular, Institut Universitari de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain
| | - Noelia Pastor-Cantizano
- Departament de Bioquímica i Biologia Molecular, Institut Universitari de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain
| | - Ismael Mingarro
- Departament de Bioquímica i Biologia Molecular, Institut Universitari de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain.
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2
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Sobe RC, Scharf BE. The swimming defect caused by the absence of the transcriptional regulator LdtR in Sinorhizobium meliloti is restored by mutations in the motility genes motA and motS. Mol Microbiol 2024; 121:954-970. [PMID: 38458990 DOI: 10.1111/mmi.15247] [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: 12/28/2023] [Revised: 02/13/2024] [Accepted: 02/17/2024] [Indexed: 03/10/2024]
Abstract
The flagellar motor is a powerful macromolecular machine used to propel bacteria through various environments. We determined that flagellar motility of the alpha-proteobacterium Sinorhizobium meliloti is nearly abolished in the absence of the transcriptional regulator LdtR, known to influence peptidoglycan remodeling and stress response. LdtR does not regulate motility gene transcription. Remarkably, the motility defects of the ΔldtR mutant can be restored by secondary mutations in the motility gene motA or a previously uncharacterized gene in the flagellar regulon, which we named motS. MotS is not essential for S. meliloti motility and may serve an accessory role in flagellar motor function. Structural modeling predicts that MotS comprised an N-terminal transmembrane segment, a long-disordered region, and a conserved β-sandwich domain. The C terminus of MotS is localized in the periplasm. Genetics based substitution of MotA with MotAG12S also restored the ΔldtR motility defect. The MotAG12S variant protein features a local polarity shift at the periphery of the MotAB stator units. We propose that MotS may be required for optimal alignment of stators in wild-type flagellar motors but becomes detrimental in cells with altered peptidoglycan. Similarly, the polarity shift in stator units composed of MotB/MotAG12S might stabilize its interaction with altered peptidoglycan.
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Affiliation(s)
- Richard C Sobe
- Department of Biological Sciences, Life Sciences I, Virginia Tech, Blacksburg, Virginia, USA
| | - Birgit E Scharf
- Department of Biological Sciences, Life Sciences I, Virginia Tech, Blacksburg, Virginia, USA
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3
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Melchionna M, Ganusova EE, Harmon N, Alexandre G. TrhA, a bacterial progestin and adiponectin receptor homolog, couples membrane energetics homeostasis and unsaturated fatty acid metabolism. J Bacteriol 2024; 206:e0039723. [PMID: 38054739 PMCID: PMC10810207 DOI: 10.1128/jb.00397-23] [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: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 12/07/2023] Open
Abstract
Members of the widely conserved progestin and adipoQ receptor (PAQR) family function to maintain membrane homeostasis: membrane fluidity and fatty acid composition in eukaryotes and membrane energetics and fatty acid composition in bacteria. All PAQRs consist of a core seven transmembrane domain structure and five conserved amino acids (three histidines, one serine, and one aspartic acid) predicted to form a hydrolase-like catalytic site. PAQR homologs in Bacteria (called TrhA, for transmembrane homeostasis protein A) maintain homeostasis of membrane charge gradients, like the membrane potential and proton gradient that comprise the proton motive force, but their molecular mechanisms are not yet understood. Here, we show that TrhA in Escherichia coli has a periplasmic C-terminus, which places the five conserved residues shared by all PAQRs at the cytoplasmic interface of the membrane. Here, we characterize several conserved residues predicted to form an active site by site-directed mutagenesis. We also identify a specific role for TrhA in modulating unsaturated fatty acid biosynthesis with conserved residues required to either promote or reduce the abundance of unsaturated fatty acids. We also identify distinct roles for the conserved residues in supporting TrhA's role in maintaining membrane energetics homeostasis that suggest that both functions are intertwined and probably partly dependent on one another. An analysis of domain architecture of TrhA-like domains in Bacteria further supports a function of TrhA linking membrane energetics homeostasis with biosynthesis of unsaturated fatty acid in the membrane. IMPORTANCE Progestin and adipoQ receptor (PAQR) family proteins are evolutionary conserved regulators of membrane homeostasis and have been best characterized in eukaryotes. Bacterial PAQR homologs, named TrhA (transmembrane homeostasis protein A), regulate membrane energetics homeostasis through an unknown mechanism. Here, we present evidence linking TrhA to both membrane energetics homeostasis and unsaturated fatty acid biosynthesis. Analysis of domain architecture together with experimental evidence suggests a model where TrhA activity on unsaturated fatty acid biosynthesis is regulated by changes in membrane energetics to dynamically adjust membrane homeostasis.
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Affiliation(s)
- Maddison Melchionna
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Elena E. Ganusova
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Neyland Harmon
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Gladys Alexandre
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
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4
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González-Magaña A, Altuna J, Queralt-Martín M, Largo E, Velázquez C, Montánchez I, Bernal P, Alcaraz A, Albesa-Jové D. The P. aeruginosa effector Tse5 forms membrane pores disrupting the membrane potential of intoxicated bacteria. Commun Biol 2022; 5:1189. [PMID: 36335275 PMCID: PMC9637101 DOI: 10.1038/s42003-022-04140-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 10/20/2022] [Indexed: 11/08/2022] Open
Abstract
The type VI secretion system (T6SS) of Pseudomonas aeruginosa injects effector proteins into neighbouring competitors and host cells, providing a fitness advantage that allows this opportunistic nosocomial pathogen to persist and prevail during the onset of infections. However, despite the high clinical relevance of P. aeruginosa, the identity and mode of action of most P. aeruginosa T6SS-dependent effectors remain to be discovered. Here, we report the molecular mechanism of Tse5-CT, the toxic auto-proteolytic product of the P. aeruginosa T6SS exported effector Tse5. Our results demonstrate that Tse5-CT is a pore-forming toxin that can transport ions across the membrane, causing membrane depolarisation and bacterial death. The membrane potential regulates a wide range of essential cellular functions; therefore, membrane depolarisation is an efficient strategy to compete with other microorganisms in polymicrobial environments. The Pseudomonas aeruginosa Type 6 secretion effector Tse5 forms pores in the cytoplasmic membrane when ectopically produced and hence has a bacteriolytic effect by depolarising the inner membrane potential.
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Affiliation(s)
- Amaia González-Magaña
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - Jon Altuna
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - María Queralt-Martín
- Laboratory of Molecular Biophysics, Department of Physics, University Jaume I, 12071, Castellón, Spain
| | - Eneko Largo
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain.,Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940, Leioa, Spain
| | - Carmen Velázquez
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain
| | - Itxaso Montánchez
- Departamento de Inmunología, Microbiología y Parasitología, University of the Basque Country, 48940, Leioa, Spain
| | - Patricia Bernal
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, 41012, Sevilla, Spain
| | - Antonio Alcaraz
- Laboratory of Molecular Biophysics, Department of Physics, University Jaume I, 12071, Castellón, Spain
| | - David Albesa-Jové
- Fundación Biofísica Bizkaia/Biofisika Bizkaia Fundazioa (FBB) and Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), University of the Basque Country, 48940, Leioa, Spain. .,Ikerbasque, Basque Foundation for Science, 48013, Bilbao, Spain.
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5
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Sobe RC, Gilbert C, Vo L, Alexandre G, Scharf BE. FliL and its paralog MotF have distinct roles in the stator activity of the Sinorhizobium meliloti flagellar motor. Mol Microbiol 2022; 118:223-243. [PMID: 35808893 PMCID: PMC9541039 DOI: 10.1111/mmi.14964] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 11/30/2022]
Abstract
The bacterial flagellum is a complex macromolecular machine that drives bacteria through diverse fluid environments. Although many components of the flagellar motor are conserved across species, the roles of FliL are numerous and species‐specific. Here, we have characterized an additional player required for flagellar motor function in Sinorhizobium meliloti, MotF, which we have identified as a FliL paralog. We performed a comparative analysis of MotF and FliL, identified interaction partners through bacterial two‐hybrid and pull‐down assays, and investigated their roles in motility and motor rotation. Both proteins form homooligomers, and interact with each other, and with the stator proteins MotA and MotB. The ∆motF mutant exhibits normal flagellation but its swimming behavior and flagellar motor activity are severely impaired and erratic. In contrast, the ∆fliL mutant is mostly aflagellate and nonmotile. Amino acid substitutions in cytoplasmic regions of MotA or disruption of the proton channel plug of MotB partially restored motor activity to the ∆motF but not the ∆fliL mutant. Altogether, our findings indicate that both, MotF and FliL, are essential for flagellar motor torque generation in S. meliloti. FliL may serve as a scaffold for stator integration into the motor, and MotF is required for proton channel modulation.
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Affiliation(s)
- Richard C Sobe
- Department of Biological Sciences, Life Sciences I, Virginia Tech, Blacksburg, VA, USA
| | - Crystal Gilbert
- Department of Biological Sciences, Life Sciences I, Virginia Tech, Blacksburg, VA, USA
| | - Lam Vo
- Department of Biochemistry and Cell and Molecular Biology, University of Tennessee at Knoxville, Knoxville, TN, USA.,Present address: Molecular Cellular and Developmental Biology and Physics, Yale Science Building, Yale University, New Haven, CT, USA
| | - Gladys Alexandre
- Department of Biochemistry and Cell and Molecular Biology, University of Tennessee at Knoxville, Knoxville, TN, USA
| | - Birgit E Scharf
- Department of Biological Sciences, Life Sciences I, Virginia Tech, Blacksburg, VA, USA
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Maczuga NT, Tran ENH, Morona R. Topology of the Shigella flexneri Enterobacterial Common Antigen polymerase WzyE. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35470793 DOI: 10.1099/mic.0.001183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Enterobacteriales have evolved a specialized outer membrane polysaccharide [Enterobacterial Common Antigen (ECA)] which allows them to persist in various environmental niches. Biosynthesis of ECA initiates on the cytoplasmic leaflet of the inner membrane (IM) where glycosyltransferases assemble ECA repeat units (RUs). Complete RUs are then translocated across the IM and assembled into polymers by ECA-specific homologues of the Wzy-dependent pathway. Consisting of the membrane proteins Wzx, Wzy and Wzz, the Wzy-dependent pathway is the most common polysaccharide biosynthetic pathway in Gram-negative bacteria where it is most notably involved in LPS O antigen (Oag) biosynthesis. As such, the majority of research directed towards these proteins has been orientated towards Oag biosynthetic homologues with little directed towards ECA homologues. Belonging to the Shape, Elongation, Division and Sporulation (SEDS) protein family, Wzy proteins are polymerases, and are characterized as possessing little or no peptide homology among homologues as well as being polytopic membrane proteins with functionally relevant residues within periplasmic loops, as defined by C-terminal reporter fusion topology mapping. Here, we present the first the first major study into the ECA polymerase WzyE. Multiple sequence alignments and topology mapping showed that WzyE is unlike WzyB proteins involved with Oag biosynthesis WzyE displays high peptide conservation across Enterobacteriales. In silico structures and reporter mapping allowed us to identify possible functionally conserved residues with WzyESF's periplasmic loops, which we showed were crucial for its function. This work provides novel insight into Wzy proteins and suggests that WzyE is an optimal model to investigate Wzy proteins and the Wzy-dependent pathway.
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Affiliation(s)
- Nicholas T Maczuga
- Department of Molecular and Biomedical Sciences, Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Elizabeth N H Tran
- Department of Molecular and Biomedical Sciences, Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Renato Morona
- Department of Molecular and Biomedical Sciences, Research Centre for Infectious Diseases, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia
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Boldrin F, Cioetto Mazzabò L, Lanéelle MA, Rindi L, Segafreddo G, Lemassu A, Etienne G, Conflitti M, Daffé M, Garzino Demo A, Manganelli R, Marrakchi H, Provvedi R. LysX2 is a Mycobacterium tuberculosis membrane protein with an extracytoplasmic MprF-like domain. BMC Microbiol 2022; 22:85. [PMID: 35365094 PMCID: PMC8974105 DOI: 10.1186/s12866-022-02493-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 03/11/2022] [Indexed: 11/17/2022] Open
Abstract
Background Aminoacyl-phosphatidylglycerol (aaPG) synthases are bacterial enzymes that usually catalyze transfer of aminoacyl residues to the plasma membrane phospholipid phosphatidylglycerol (PG). The result is introduction of positive charges onto the cytoplasmic membrane, yielding reduced affinity towards cationic antimicrobial peptides, and increased resistance to acidic environments. Therefore, these enzymes represent an important defense mechanism for many pathogens, including Staphylococcus aureus and Mycobacterium tuberculosis (Mtb), which are known to encode for lysyl-(Lys)-PG synthase MprF and LysX, respectively. Here, we used a combination of bioinformatic, genetic and bacteriological methods to characterize a protein encoded by the Mtb genome, Rv1619, carrying a domain with high similarity to MprF-like domains, suggesting that this protein could be a new aaPG synthase family member. However, unlike homologous domains of MprF and LysX that are positioned in the cytoplasm, we predicted that the MprF-like domain in LysX2 is in the extracytoplasmic region. Results Using genetic fusions to the Escherichia coli proteins PhoA and LacZ of LysX2, we confirmed this unique membrane topology, as well as LysX and MprF as benchmarks. Expression of lysX2 in Mycobacterium smegmatis increased cell resistance to human β-defensin 2 and sodium nitrite, enhanced cell viability and delayed biofilm formation in acidic pH environment. Remarkably, MtLysX2 significantly reduced the negative charge on the bacterial surface upon exposure to an acidic environment. Additionally, we found LysX2 orthologues in major human pathogens and in rapid-growing mycobacteria frequently associated with human infections, but not in environmental and non-pathogenic mycobacteria. Conclusions Overall, our data suggest that LysX2 is a prototype of a new class within the MprF-like protein family that likely enhances survival of the pathogenic species through its catalytic domain which is exposed to the extracytoplasmic side of the cell membrane and is required to decrease the negative charge on the bacterial surface through a yet uncharacterized mechanism. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-022-02493-2.
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Affiliation(s)
| | | | - Marie-Antoinette Lanéelle
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Laura Rindi
- Department of Translational Research, University of Pisa, Pisa, Italy
| | - Greta Segafreddo
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Anne Lemassu
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Gilles Etienne
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Marta Conflitti
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Mamadou Daffé
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Alfredo Garzino Demo
- Department of Molecular Medicine, University of Padua, Padua, Italy.,Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | | | - Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
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8
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Gallois N, Alpha-Bazin B, Bremond N, Ortet P, Barakat M, Piette L, Mohamad Ali A, Lemaire D, Legrand P, Theodorakopoulos N, Floriani M, Février L, Den Auwer C, Arnoux P, Berthomieu C, Armengaud J, Chapon V. Discovery and characterization of UipA, a uranium- and iron-binding PepSY protein involved in uranium tolerance by soil bacteria. THE ISME JOURNAL 2022; 16:705-716. [PMID: 34556817 PMCID: PMC8857325 DOI: 10.1038/s41396-021-01113-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 09/01/2021] [Accepted: 09/08/2021] [Indexed: 02/08/2023]
Abstract
Uranium is a naturally occurring radionuclide. Its redistribution, primarily due to human activities, can have adverse effects on human and non-human biota, which poses environmental concerns. The molecular mechanisms of uranium tolerance and the cellular response induced by uranium exposure in bacteria are not yet fully understood. Here, we carried out a comparative analysis of four actinobacterial strains isolated from metal and radionuclide-rich soils that display contrasted uranium tolerance phenotypes. Comparative proteogenomics showed that uranyl exposure affects 39-47% of the total proteins, with an impact on phosphate and iron metabolisms and membrane proteins. This approach highlighted a protein of unknown function, named UipA, that is specific to the uranium-tolerant strains and that had the highest positive fold-change upon uranium exposure. UipA is a single-pass transmembrane protein and its large C-terminal soluble domain displayed a specific, nanomolar binding affinity for UO22+ and Fe3+. ATR-FTIR and XAS-spectroscopy showed that mono and bidentate carboxylate groups of the protein coordinated both metals. The crystal structure of UipA, solved in its apo state and bound to uranium, revealed a tandem of PepSY domains in a swapped dimer, with a negatively charged face where uranium is bound through a set of conserved residues. This work reveals the importance of UipA and its PepSY domains in metal binding and radionuclide tolerance.
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Affiliation(s)
- Nicolas Gallois
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Béatrice Alpha-Bazin
- grid.5583.b0000 0001 2299 8025Département Médicaments et Technologies pour la Santé (DMTS), Université Paris-Saclay, CEA, INRAE, SPI, 30200 Bagnols-sur-Cèze, France
| | - Nicolas Bremond
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Philippe Ortet
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Mohamed Barakat
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Laurie Piette
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Abbas Mohamad Ali
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - David Lemaire
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Pierre Legrand
- grid.426328.9Synchrotron SOLEIL. L’Orme des Merisiers Saint-Aubin. BP 48, 91192 Gif-sur-Yvette, France
| | - Nicolas Theodorakopoulos
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France ,grid.418735.c0000 0001 1414 6236IRSN, PSE-ENV/SRTE/LR2T, B.P. 3, 13115 Saint Paul-lez-Durance, Cedex France
| | - Magali Floriani
- grid.418735.c0000 0001 1414 6236IRSN, PSE-ENV/SRTE/LECO, B.P. 3, 13115 Saint Paul-lez-Durance, Cedex France
| | - Laureline Février
- grid.418735.c0000 0001 1414 6236IRSN, PSE-ENV/SRTE/LR2T, B.P. 3, 13115 Saint Paul-lez-Durance, Cedex France
| | - Christophe Den Auwer
- grid.462124.70000 0004 0384 8488Université Côte d’Azur, CNRS, ICN, 06108 Nice, France
| | - Pascal Arnoux
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Catherine Berthomieu
- grid.5399.60000 0001 2176 4817Aix Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul-Lez-Durance, France
| | - Jean Armengaud
- grid.5583.b0000 0001 2299 8025Département Médicaments et Technologies pour la Santé (DMTS), Université Paris-Saclay, CEA, INRAE, SPI, 30200 Bagnols-sur-Cèze, France
| | - Virginie Chapon
- Aix Marseille Université, CEA, CNRS, BIAM, 13108, Saint Paul-Lez-Durance, France.
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9
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Single Amino Acid Replacements in RocA Disrupt Protein-Protein Interactions To Alter the Molecular Pathogenesis of Group A Streptococcus. Infect Immun 2020; 88:IAI.00386-20. [PMID: 32817331 DOI: 10.1128/iai.00386-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 08/12/2020] [Indexed: 12/31/2022] Open
Abstract
Group A Streptococcus (GAS) is a human-specific pathogen and major cause of disease worldwide. The molecular pathogenesis of GAS, like many pathogens, is dependent on the coordinated expression of genes encoding different virulence factors. The control of virulence regulator/sensor (CovRS) two-component system is a major virulence regulator of GAS that has been extensively studied. More recent investigations have also involved regulator of Cov (RocA), a regulatory accessory protein to CovRS. RocA interacts, in some manner, with CovRS; however, the precise molecular mechanism is unknown. Here, we demonstrate that RocA is a membrane protein containing seven transmembrane helices with an extracytoplasmically located N terminus and cytoplasmically located C terminus. For the first time, we demonstrate that RocA directly interacts with itself (RocA) and CovS, but not CovR, in intact cells. Single amino acid replacements along the entire length of RocA disrupt RocA-RocA and RocA-CovS interactions to significantly alter the GAS virulence phenotype as defined by secreted virulence factor activity in vitro and tissue destruction and mortality in vivo In summary, we show that single amino acid replacements in a regulatory accessory protein can affect protein-protein interactions to significantly alter the virulence of a major human pathogen.
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10
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Motta Nascimento B, Nair NU. Characterization of a membrane enzymatic complex for heterologous production of poly-γ-glutamate in E. coli. Metab Eng Commun 2020; 11:e00144. [PMID: 32963960 PMCID: PMC7490850 DOI: 10.1016/j.mec.2020.e00144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/10/2020] [Accepted: 08/20/2020] [Indexed: 11/06/2022] Open
Abstract
Poly-γ-glutamic acid (PGA) produced by many Bacillus species is a polymer with many distinct and desirable characteristics. However, the multi-subunit enzymatic complex responsible for its synthesis, PGA Synthetase (PGS), has not been well characterized yet, in native nor in recombinant contexts. Elucidating structural and functional properties are crucial for future engineering efforts aimed at altering the catalytic properties of this enzyme. This study focuses on expressing the enzyme heterologously in the Escherichia coli membrane and characterizing localization, orientation, and activity of this heterooligomeric enzyme complex. In E. coli, we were able to produce high molecular weight PGA polymers with minimal degradation at titers of approximately 13 mg/L in deep-well microtiter batch cultures. Using fusion proteins, we observed, for the first time, the association and orientation of the different subunits with the inner cell membrane. These results provide fundamental structural information on this poorly studied enzyme complex and will aid future fundamental studies and engineering efforts. Successfully expressed active poly-γ-glutamate synthetase (PGS) in E. coli. Confirmed PGS localization at inner membrane of E. coli. Elucidated topology of PGS components in E. coli membrane. Culture and expression in microplates might allow future screening of a high number of samples. Faster production of poly-γ-glutamate in E. coli supernatant compared to B. subtilis.
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Affiliation(s)
- Bruno Motta Nascimento
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA, 02155, USA
| | - Nikhil U Nair
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA, 02155, USA
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Rajagopalan K, Dworkin J. Escherichia coli YegI is a novel Ser/Thr kinase lacking conserved motifs that localizes to the inner membrane. FEBS Lett 2020; 594:3530-3541. [PMID: 32888201 DOI: 10.1002/1873-3468.13920] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/20/2020] [Accepted: 08/20/2020] [Indexed: 12/14/2022]
Abstract
In bacteria, signaling phosphorylation is thought to occur primarily on His and Asp residues. However, phosphoproteomic surveys in phylogenetically diverse bacteria over the past decade have identified numerous proteins that are phosphorylated on Ser and/or Thr residues. Consistently, genes encoding Ser/Thr kinases are present in many bacterial genomes such as in the Escherichia coli genome, which encodes at least three Ser/Thr kinases. Here, we identify a previously uncharacterized ORF, yegI, and demonstrate that it encodes a novel Ser/Thr kinase. YegI lacks several conserved motifs including residues important for Mg2+ binding seen in other bacterial Ser/Thr kinases, suggesting that the consensus may be too stringent. We further find that YegI is a two-pass membrane protein with both N- and C termini located intracellularly.
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Affiliation(s)
- Krithika Rajagopalan
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Jonathan Dworkin
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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Britton AP, van der Ende SR, van Belkum MJ, Martin‐Visscher LA. The membrane topology of immunity proteins for the two-peptide bacteriocins carnobacteriocin XY, lactococcin G, and lactococcin MN shows structural diversity. Microbiologyopen 2020; 9:e00957. [PMID: 31667956 PMCID: PMC6957408 DOI: 10.1002/mbo3.957] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/02/2019] [Accepted: 10/03/2019] [Indexed: 11/20/2022] Open
Abstract
The two-peptide bacteriocins produced by Gram-positive bacteria require two different peptides, present in equimolar amounts, to elicit optimal antimicrobial activity. Producer organisms are protected from their bacteriocin by a dedicated immunity protein. The immunity proteins for two-peptide bacteriocins contain putative transmembrane domains (TMDs) and might therefore be associated with the membrane. The immunity protein CbnZ for the two-peptide bacteriocin carnobacteriocin XY (CbnXY) was identified by heterologously expressing the cbnZ gene in sensitive host strains. Using protein topology prediction methods and the dual pho-lac reporter system, we mapped out the membrane topology of CbnZ, along with those of the immunity proteins LagC and LciM for the two-peptide bacteriocins lactococcin G and lactococcin MN, respectively. Our results reveal wide structural variety between these immunity proteins that can contain as little as one TMD or as many as four TMDs.
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Affiliation(s)
| | - Sarah R. van der Ende
- Department of ChemistryThe King's UniversityEdmontonABCanada
- Present address:
Department of Biochemistry & Molecular BiologyDalhousie UniversityHalifaxNSCanada
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13
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Bojer MS, Wacnik K, Kjelgaard P, Gallay C, Bottomley AL, Cohn MT, Lindahl G, Frees D, Veening JW, Foster SJ, Ingmer H. SosA inhibits cell division in Staphylococcus aureus in response to DNA damage. Mol Microbiol 2019; 112:1116-1130. [PMID: 31290194 PMCID: PMC6851548 DOI: 10.1111/mmi.14350] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2019] [Indexed: 01/10/2023]
Abstract
Inhibition of cell division is critical for viability under DNA‐damaging conditions. DNA damage induces the SOS response that in bacteria inhibits cell division while repairs are being made. In coccoids, such as the human pathogen, Staphylococcus aureus, this process remains poorly studied. Here, we identify SosA as the staphylococcal SOS‐induced cell division inhibitor. Overproduction of SosA inhibits cell division, while sosA inactivation sensitizes cells to genotoxic stress. SosA is a small, predicted membrane protein with an extracellular C‐terminal domain in which point mutation of residues that are conserved in staphylococci and major truncations abolished the inhibitory activity. In contrast, a minor truncation led to SosA accumulation and a strong cell division inhibitory activity, phenotypically similar to expression of wild‐type SosA in a CtpA membrane protease mutant. This suggests that the extracellular C‐terminus of SosA is required both for cell division inhibition and for turnover of the protein. Microscopy analysis revealed that SosA halts cell division and synchronizes the cell population at a point where division proteins such as FtsZ and EzrA are localized at midcell, and the septum formation is initiated but unable to progress to closure. Thus, our findings show that SosA is central in cell division regulation in staphylococci.
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Affiliation(s)
- Martin S Bojer
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Centre for Bacterial Stress Response and Persistence, University of Copenhagen, Copenhagen, Denmark
| | - Katarzyna Wacnik
- Department of Molecular Biology and Biotechnology, The Krebs Institute, University of Sheffield, Sheffield, UK
| | - Peter Kjelgaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Clement Gallay
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Amy L Bottomley
- Department of Molecular Biology and Biotechnology, The Krebs Institute, University of Sheffield, Sheffield, UK
| | - Marianne T Cohn
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gunnar Lindahl
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dorte Frees
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jan-Willem Veening
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Simon J Foster
- Department of Molecular Biology and Biotechnology, The Krebs Institute, University of Sheffield, Sheffield, UK
| | - Hanne Ingmer
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Centre for Bacterial Stress Response and Persistence, University of Copenhagen, Copenhagen, Denmark
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