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Norris V, Kayser C, Muskhelishvili G, Konto-Ghiorghi Y. The roles of nucleoid-associated proteins and topoisomerases in chromosome structure, strand segregation, and the generation of phenotypic heterogeneity in bacteria. FEMS Microbiol Rev 2023; 47:fuac049. [PMID: 36549664 DOI: 10.1093/femsre/fuac049] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/06/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
How to adapt to a changing environment is a fundamental, recurrent problem confronting cells. One solution is for cells to organize their constituents into a limited number of spatially extended, functionally relevant, macromolecular assemblies or hyperstructures, and then to segregate these hyperstructures asymmetrically into daughter cells. This asymmetric segregation becomes a particularly powerful way of generating a coherent phenotypic diversity when the segregation of certain hyperstructures is with only one of the parental DNA strands and when this pattern of segregation continues over successive generations. Candidate hyperstructures for such asymmetric segregation in prokaryotes include those containing the nucleoid-associated proteins (NAPs) and the topoisomerases. Another solution to the problem of creating a coherent phenotypic diversity is by creating a growth-environment-dependent gradient of supercoiling generated along the replication origin-to-terminus axis of the bacterial chromosome. This gradient is modulated by transcription, NAPs, and topoisomerases. Here, we focus primarily on two topoisomerases, TopoIV and DNA gyrase in Escherichia coli, on three of its NAPs (H-NS, HU, and IHF), and on the single-stranded binding protein, SSB. We propose that the combination of supercoiling-gradient-dependent and strand-segregation-dependent topoisomerase activities result in significant differences in the supercoiling of daughter chromosomes, and hence in the phenotypes of daughter cells.
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Affiliation(s)
- Vic Norris
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Clara Kayser
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Georgi Muskhelishvili
- Agricultural University of Georgia, School of Natural Sciences, 0159 Tbilisi, Georgia
| | - Yoan Konto-Ghiorghi
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
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2
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Perez D, Dahlberg PD, Wang J, Sartor AM, Borden JS, Shapiro L, Moerner WE. Identification and demonstration of roGFP2 as an environmental sensor for cryogenic correlative light and electron microscopy. J Struct Biol 2022; 214:107881. [PMID: 35811036 PMCID: PMC9452478 DOI: 10.1016/j.jsb.2022.107881] [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: 02/22/2022] [Revised: 06/29/2022] [Accepted: 07/04/2022] [Indexed: 10/17/2022]
Abstract
Cryogenic correlative light and electron microscopy (cryo-CLEM) seeks to leverage orthogonal information present in two powerful imaging modalities. While recent advances in cryogenic electron microscopy (cryo-EM) allow for the visualization and identification of structures within cells at the nanometer scale, information regarding the cellular environment, such as pH, membrane potential, ionic strength, etc., which influences the observed structures remains absent. Fluorescence microscopy can potentially be used to reveal this information when specific labels, known as fluorescent biosensors, are used, but there has been minimal use of such biosensors in cryo-CLEM to date. Here we demonstrate the applicability of one such biosensor, the fluorescent protein roGFP2, for cryo-CLEM experiments. At room temperature, the ratio of roGFP2 emission brightness when excited at 425 nm or 488 nm is known to report on the local redox potential. When samples containing roGFP2 are rapidly cooled to 77 K in a manner compatible with cryo-EM, the ratio of excitation peaks remains a faithful indicator of the redox potential at the time of freezing. Using purified protein in different oxidizing/reducing environments, we generate a calibration curve which can be used to analyze in situ measurements. As a proof-of-principle demonstration, we investigate the oxidation/reduction state within vitrified Caulobacter crescentus cells. The polar organizing protein Z (PopZ) localizes to the polar regions of C. crescentus where it is known to form a distinct microdomain. By expressing an inducible roGFP2-PopZ fusion we visualize individual microdomains in the context of their redox environment.
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Affiliation(s)
- Davis Perez
- Department of Chemistry, Stanford University, United States
| | - Peter D Dahlberg
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, United States
| | - Jiarui Wang
- Department of Chemistry, Stanford University, United States; Department of Developmental Biology, Stanford University, United States
| | | | - Julia S Borden
- Department of Molecular and Cell Biology, University of California, Berkeley, United States
| | - Lucy Shapiro
- Department of Developmental Biology, Stanford University, United States
| | - W E Moerner
- Department of Chemistry, Stanford University, United States
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3
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Fatima NI, Fazili KM, Bhat NH. Proteolysis dependent cell cycle regulation in Caulobacter crescentus. Cell Div 2022; 17:3. [PMID: 35365160 PMCID: PMC8973945 DOI: 10.1186/s13008-022-00078-z] [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: 08/21/2021] [Accepted: 02/22/2022] [Indexed: 11/10/2022] Open
Abstract
Caulobacter crescentus, a Gram-negative alpha-proteobacterium, has surfaced as a powerful model system for unraveling molecular networks that control the bacterial cell cycle. A straightforward synchronization protocol and existence of many well-defined developmental markers has allowed the identification of various molecular circuits that control the underlying differentiation processes executed at the level of transcription, translation, protein localization and dynamic proteolysis. The oligomeric AAA+ protease ClpXP is a well-characterized example of an enzyme that exerts post-translational control over a number of pathways. Also, the proteolytic pathways of its candidate proteins are reported to play significant roles in regulating cell cycle and protein quality control. A detailed evaluation of the impact of its proteolysis on various regulatory networks of the cell has uncovered various significant cellular roles of this protease in C. crescentus. A deeper insight into the effects of regulatory proteolysis with emphasis on cell cycle progression could shed light on how cells respond to environmental cues and implement developmental switches. Perturbation of this network of molecular machines is also associated with diseases such as bacterial infections. Thus, research holds immense implications in clinical translation and health, representing a promising area for clinical advances in the diagnosis, therapeutics and prognosis.
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Affiliation(s)
- Nida I Fatima
- Department of Biotechnology, University of Kashmir, Hazratbal, Srinagar, Jammu and Kashmir, 190006, India
| | - Khalid Majid Fazili
- Department of Biotechnology, University of Kashmir, Hazratbal, Srinagar, Jammu and Kashmir, 190006, India
| | - Nowsheen Hamid Bhat
- Department of Biotechnology, Central University of Kashmir, Ganderbal, Jammu and Kashmir, 191201, India.
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4
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The ChvG-ChvI and NtrY-NtrX Two-Component Systems Coordinately Regulate Growth of Caulobacter crescentus. J Bacteriol 2021; 203:e0019921. [PMID: 34124942 DOI: 10.1128/jb.00199-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Two-component signaling systems (TCSs) are comprised of a sensory histidine kinase and a response regulator protein. In response to environmental changes, sensor kinases directly phosphorylate their cognate response regulator to affect gene expression. Bacteria typically express multiple TCSs that are insulated from one another and regulate distinct physiological processes. There are examples of cross-regulation between TCSs, but this phenomenon remains relatively unexplored. We have identified regulatory links between the ChvG-ChvI (ChvGI) and NtrY-NtrX (NtrYX) TCSs, which control important and often overlapping processes in alphaproteobacteria, including maintenance of the cell envelope. Deletion of chvG and chvI in Caulobacter crescentus limited growth in defined medium, and a selection for genetic suppressors of this growth phenotype uncovered interactions among chvGI, ntrYX, and ntrZ, which encodes a previously uncharacterized periplasmic protein. Significant overlap in the experimentally defined ChvI and NtrX transcriptional regulons provided support for the observed genetic connections between ntrYX and chvGI. Moreover, we present evidence that the growth defect of strains lacking chvGI is influenced by the phosphorylation state of NtrX and, to some extent, by levels of the TonB-dependent receptor ChvT. Measurements of NtrX phosphorylation in vivo indicated that NtrZ is an upstream regulator of NtrY and that NtrY primarily functions as an NtrX phosphatase. We propose a model in which NtrZ functions in the periplasm to inhibit NtrY phosphatase activity; regulation of phosphorylated NtrX levels by NtrZ and NtrY provides a mechanism to modulate and balance expression of the NtrX and ChvI regulons under different growth conditions. IMPORTANCE TCSs enable bacteria to regulate gene expression in response to physiochemical changes in their environment. The ChvGI and NtrYX TCSs regulate diverse pathways associated with pathogenesis, growth, and cell envelope function in many alphaproteobacteria. We used Caulobacter crescentus as a model to investigate regulatory connections between ChvGI and NtrYX. Our work defined the ChvI transcriptional regulon in C. crescentus and revealed a genetic interaction between ChvGI and NtrYX, whereby modulation of NtrYX signaling affects the survival of cells lacking ChvGI. In addition, we identified NtrZ as a periplasmic inhibitor of NtrY phosphatase activity in vivo. Our work establishes C. crescentus as an excellent model to investigate multilevel regulatory connections between ChvGI and NtrYX in alphaproteobacteria.
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5
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Maertens L, Cherry P, Tilquin F, Van Houdt R, Matroule JY. Environmental Conditions Modulate the Transcriptomic Response of Both Caulobacter crescentus Morphotypes to Cu Stress. Microorganisms 2021; 9:1116. [PMID: 34064119 PMCID: PMC8224329 DOI: 10.3390/microorganisms9061116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 12/13/2022] Open
Abstract
Bacteria encounter elevated copper (Cu) concentrations in multiple environments, varying from mining wastes to antimicrobial applications of copper. As the role of the environment in the bacterial response to Cu ion exposure remains elusive, we used a tagRNA-seq approach to elucidate the disparate responses of two morphotypes of Caulobacter crescentus NA1000 to moderate Cu stress in a complex rich (PYE) medium and a defined poor (M2G) medium. The transcriptome was more responsive in M2G, where we observed an extensive oxidative stress response and reconfiguration of the proteome, as well as the induction of metal resistance clusters. In PYE, little evidence was found for an oxidative stress response, but several transport systems were differentially expressed, and an increased need for histidine was apparent. These results show that the Cu stress response is strongly dependent on the cellular environment. In addition, induction of the extracytoplasmic function sigma factor SigF and its regulon was shared by the Cu stress responses in both media, and its central role was confirmed by the phenotypic screening of a sigF::Tn5 mutant. In both media, stalked cells were more responsive to Cu stress than swarmer cells, and a stronger basal expression of several cell protection systems was noted, indicating that the swarmer cell is inherently more Cu resistant. Our approach also allowed for detecting several new transcription start sites, putatively indicating small regulatory RNAs, and additional levels of Cu-responsive regulation.
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Affiliation(s)
- Laurens Maertens
- Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), 2400 Mol, Belgium; (L.M.); (R.V.H.)
- Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, 5000 Namur, Belgium; (P.C.); (F.T.)
| | - Pauline Cherry
- Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, 5000 Namur, Belgium; (P.C.); (F.T.)
| | - Françoise Tilquin
- Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, 5000 Namur, Belgium; (P.C.); (F.T.)
| | - Rob Van Houdt
- Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), 2400 Mol, Belgium; (L.M.); (R.V.H.)
| | - Jean-Yves Matroule
- Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, 5000 Namur, Belgium; (P.C.); (F.T.)
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6
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When the metabolism meets the cell cycle in bacteria. Curr Opin Microbiol 2021; 60:104-113. [PMID: 33677348 DOI: 10.1016/j.mib.2021.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/20/2022]
Abstract
Nutrients availability is the sinews of the war for single microbial cells, driving growth and cell cycle progression. Therefore, coordinating cellular processes with nutrients availability is crucial, not only to survive upon famine or fluctuating conditions but also to rapidly thrive and colonize plentiful environments. While metabolism is traditionally seen as a set of chemical reactions taking place in cells to extract energy and produce building blocks from available nutrients, numerous connections between metabolic pathways and cell cycle phases have been documented. The few regulatory systems described at the molecular levels show that regulation is mediated either by a second messenger molecule or by a metabolite and/or a metabolic enzyme. In the latter case, a secondary moonlighting regulatory function evolved independently of the primary catalytic function of the enzyme. In this review, we summarize our current understanding of the complex cross-talks between metabolism and cell cycle in bacteria.
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7
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An organelle-tethering mechanism couples flagellation to cell division in bacteria. Dev Cell 2021; 56:657-670.e4. [PMID: 33600766 DOI: 10.1016/j.devcel.2021.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 12/09/2020] [Accepted: 01/20/2021] [Indexed: 11/21/2022]
Abstract
In some free-living and pathogenic bacteria, problems in the synthesis and assembly of early flagellar components can cause cell-division defects. However, the mechanism that couples cell division with the flagellar biogenesis has remained elusive. Herein, we discover the regulator MadA that controls transcription of flagellar and cell-division genes in Caulobacter crescentus. We demonstrate that MadA, a small soluble protein, binds the type III export component FlhA to promote activation of FliX, which in turn is required to license the conserved σ54-dependent transcriptional activator FlbD. While in the absence of MadA, FliX and FlbD activation is crippled, bypass mutations in FlhA restore flagellar biogenesis and cell division. Furthermore, we demonstrate that MadA safeguards the divisome stoichiometry to license cell division. We propose that MadA has a sentinel-type function that senses an early flagellar biogenesis event and, through cell-division control, ensures that a flagellated offspring emerges.
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8
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Meunier A, Cornet F, Campos M. Bacterial cell proliferation: from molecules to cells. FEMS Microbiol Rev 2021; 45:fuaa046. [PMID: 32990752 PMCID: PMC7794046 DOI: 10.1093/femsre/fuaa046] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 09/10/2020] [Indexed: 12/11/2022] Open
Abstract
Bacterial cell proliferation is highly efficient, both because bacteria grow fast and multiply with a low failure rate. This efficiency is underpinned by the robustness of the cell cycle and its synchronization with cell growth and cytokinesis. Recent advances in bacterial cell biology brought about by single-cell physiology in microfluidic chambers suggest a series of simple phenomenological models at the cellular scale, coupling cell size and growth with the cell cycle. We contrast the apparent simplicity of these mechanisms based on the addition of a constant size between cell cycle events (e.g. two consecutive initiation of DNA replication or cell division) with the complexity of the underlying regulatory networks. Beyond the paradigm of cell cycle checkpoints, the coordination between the DNA and division cycles and cell growth is largely mediated by a wealth of other mechanisms. We propose our perspective on these mechanisms, through the prism of the known crosstalk between DNA replication and segregation, cell division and cell growth or size. We argue that the precise knowledge of these molecular mechanisms is critical to integrate the diverse layers of controls at different time and space scales into synthetic and verifiable models.
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Affiliation(s)
- Alix Meunier
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
| | - François Cornet
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
| | - Manuel Campos
- Centre de Biologie Intégrative de Toulouse (CBI Toulouse), Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Université de Toulouse, UPS, CNRS, IBCG, 165 rue Marianne Grunberg-Manago, 31062 Toulouse, France
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9
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Sutormin DA, Galivondzhyan AK, Polkhovskiy AV, Kamalyan SO, Severinov KV, Dubiley SA. Diversity and Functions of Type II Topoisomerases. Acta Naturae 2021; 13:59-75. [PMID: 33959387 PMCID: PMC8084294 DOI: 10.32607/actanaturae.11058] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/09/2020] [Indexed: 11/29/2022] Open
Abstract
The DNA double helix provides a simple and elegant way to store and copy genetic information. However, the processes requiring the DNA helix strands separation, such as transcription and replication, induce a topological side-effect - supercoiling of the molecule. Topoisomerases comprise a specific group of enzymes that disentangle the topological challenges associated with DNA supercoiling. They relax DNA supercoils and resolve catenanes and knots. Here, we review the catalytic cycles, evolution, diversity, and functional roles of type II topoisomerases in organisms from all domains of life, as well as viruses and other mobile genetic elements.
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Affiliation(s)
- D. A. Sutormin
- Institute of Gene Biology RAS, Moscow, 119334 Russia
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
| | - A. K. Galivondzhyan
- Lomonosov Moscow State University, Moscow, 119991 Russia
- Institute of Molecular Genetics RAS, Moscow, 123182 Russia
| | - A. V. Polkhovskiy
- Institute of Gene Biology RAS, Moscow, 119334 Russia
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
| | - S. O. Kamalyan
- Institute of Gene Biology RAS, Moscow, 119334 Russia
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
| | - K. V. Severinov
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
- Centre for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology RAS, Moscow, 119334 Russia
- Waksman Institute for Microbiology, Piscataway, New Jersey, 08854 USA
| | - S. A. Dubiley
- Institute of Gene Biology RAS, Moscow, 119334 Russia
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Moscow, 121205 Russia
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10
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Shyp V, Dubey BN, Böhm R, Hartl J, Nesper J, Vorholt JA, Hiller S, Schirmer T, Jenal U. Reciprocal growth control by competitive binding of nucleotide second messengers to a metabolic switch in Caulobacter crescentus. Nat Microbiol 2020; 6:59-72. [PMID: 33168988 DOI: 10.1038/s41564-020-00809-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 10/02/2020] [Indexed: 12/13/2022]
Abstract
Bacteria use small signalling molecules such as (p)ppGpp or c-di-GMP to tune their physiology in response to environmental changes. It remains unclear whether these regulatory networks operate independently or whether they interact to optimize bacterial growth and survival. We report that (p)ppGpp and c-di-GMP reciprocally regulate the growth of Caulobacter crescentus by converging on a single small-molecule-binding protein, SmbA. While c-di-GMP binding inhibits SmbA, (p)ppGpp competes for the same binding site to sustain SmbA activity. We demonstrate that (p)ppGpp specifically promotes Caulobacter growth on glucose, whereas c-di-GMP inhibits glucose consumption. We find that SmbA contributes to this metabolic switch and promotes growth on glucose by quenching the associated redox stress. The identification of an effector protein that acts as a central regulatory hub for two global second messengers opens up future studies on specific crosstalk between small-molecule-based regulatory networks.
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Affiliation(s)
| | | | - Raphael Böhm
- Biozentrum, University of Basel, Basel, Switzerland
| | - Johannes Hartl
- Institute of Microbiology, ETH Zurich, Zürich, Switzerland
| | - Jutta Nesper
- Biozentrum, University of Basel, Basel, Switzerland
| | | | | | | | - Urs Jenal
- Biozentrum, University of Basel, Basel, Switzerland.
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11
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Kostyuk AI, Panova AS, Kokova AD, Kotova DA, Maltsev DI, Podgorny OV, Belousov VV, Bilan DS. In Vivo Imaging with Genetically Encoded Redox Biosensors. Int J Mol Sci 2020; 21:E8164. [PMID: 33142884 PMCID: PMC7662651 DOI: 10.3390/ijms21218164] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 12/13/2022] Open
Abstract
Redox reactions are of high fundamental and practical interest since they are involved in both normal physiology and the pathogenesis of various diseases. However, this area of research has always been a relatively problematic field in the context of analytical approaches, mostly because of the unstable nature of the compounds that are measured. Genetically encoded sensors allow for the registration of highly reactive molecules in real-time mode and, therefore, they began a new era in redox biology. Their strongest points manifest most brightly in in vivo experiments and pave the way for the non-invasive investigation of biochemical pathways that proceed in organisms from different systematic groups. In the first part of the review, we briefly describe the redox sensors that were used in vivo as well as summarize the model systems to which they were applied. Next, we thoroughly discuss the biological results obtained in these studies in regard to animals, plants, as well as unicellular eukaryotes and prokaryotes. We hope that this work reflects the amazing power of this technology and can serve as a useful guide for biologists and chemists who work in the field of redox processes.
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Affiliation(s)
- Alexander I. Kostyuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Anastasiya S. Panova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Aleksandra D. Kokova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Daria A. Kotova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Dmitry I. Maltsev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Federal Center for Cerebrovascular Pathology and Stroke, 117997 Moscow, Russia
| | - Oleg V. Podgorny
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Vsevolod V. Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Federal Center for Cerebrovascular Pathology and Stroke, 117997 Moscow, Russia
- Institute for Cardiovascular Physiology, Georg August University Göttingen, D-37073 Göttingen, Germany
| | - Dmitry S. Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.S.P.); (A.D.K.); (D.A.K.); (D.I.M.); (O.V.P.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
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12
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Bergé M, Pezzatti J, González-Ruiz V, Degeorges L, Mottet-Osman G, Rudaz S, Viollier PH. Bacterial cell cycle control by citrate synthase independent of enzymatic activity. eLife 2020; 9:52272. [PMID: 32149608 PMCID: PMC7083601 DOI: 10.7554/elife.52272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/04/2020] [Indexed: 11/17/2022] Open
Abstract
Proliferating cells must coordinate central metabolism with the cell cycle. How central energy metabolism regulates bacterial cell cycle functions is not well understood. Our forward genetic selection unearthed the Krebs cycle enzyme citrate synthase (CitA) as a checkpoint regulator controlling the G1→S transition in the polarized alpha-proteobacterium Caulobacter crescentus, a model for cell cycle regulation and asymmetric cell division. We find that loss of CitA promotes the accumulation of active CtrA, an essential cell cycle transcriptional regulator that maintains cells in G1-phase, provided that the (p)ppGpp alarmone is present. The enzymatic activity of CitA is dispensable for CtrA control, and functional citrate synthase paralogs cannot replace CitA in promoting S-phase entry. Our evidence suggests that CitA was appropriated specifically to function as a moonlighting enzyme to link central energy metabolism with S-phase entry. Control of the G1-phase by a central metabolic enzyme may be a common mechanism of cellular regulation.
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Affiliation(s)
- Matthieu Bergé
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Julian Pezzatti
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, Geneva, Switzerland
| | - Víctor González-Ruiz
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, Geneva, Switzerland.,Swiss Centre for Applied Human Toxicology (SCAHT), Basel, Switzerland
| | - Laurence Degeorges
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Geneviève Mottet-Osman
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Serge Rudaz
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, Geneva, Switzerland.,Swiss Centre for Applied Human Toxicology (SCAHT), Basel, Switzerland
| | - Patrick H Viollier
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Hartl J, Kiefer P, Kaczmarczyk A, Mittelviefhaus M, Meyer F, Vonderach T, Hattendorf B, Jenal U, Vorholt JA. Untargeted metabolomics links glutathione to bacterial cell cycle progression. Nat Metab 2020; 2:153-166. [PMID: 32090198 PMCID: PMC7035108 DOI: 10.1038/s42255-019-0166-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/17/2019] [Indexed: 12/21/2022]
Abstract
Cell cycle progression requires the coordination of cell growth, chromosome replication, and division. Consequently, a functional cell cycle must be coupled with metabolism. However, direct measurements of metabolome dynamics remained scarce, in particular in bacteria. Here, we describe an untargeted metabolomics approach with synchronized Caulobacter crescentus cells to monitor the relative abundance changes of ~400 putative metabolites as a function of the cell cycle. While the majority of metabolite pools remains homeostatic, ~14% respond to cell cycle progression. In particular, sulfur metabolism is redirected during the G1-S transition, and glutathione levels periodically change over the cell cycle with a peak in late S phase. A lack of glutathione perturbs cell size by uncoupling cell growth and division through dysregulation of KefB, a K+/H+ antiporter. Overall, we here describe the impact of the C. crescentus cell cycle progression on metabolism, and in turn relate glutathione and potassium homeostasis to timely cell division.
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Affiliation(s)
- Johannes Hartl
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland.
| | - Patrick Kiefer
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | | | | | - Fabian Meyer
- ETH Zurich, Institute of Microbiology, Zurich, Switzerland
| | - Thomas Vonderach
- ETH Zurich, Laboratory of Inorganic Chemistry, Zurich, Switzerland
| | - Bodo Hattendorf
- ETH Zurich, Laboratory of Inorganic Chemistry, Zurich, Switzerland
| | - Urs Jenal
- Biozentrum of the University of Basel, Basel, Switzerland
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14
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Reyes Ruiz LM, Fiebig A, Crosson S. Regulation of bacterial surface attachment by a network of sensory transduction proteins. PLoS Genet 2019; 15:e1008022. [PMID: 31075103 PMCID: PMC6530869 DOI: 10.1371/journal.pgen.1008022] [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: 02/12/2019] [Revised: 05/22/2019] [Accepted: 04/26/2019] [Indexed: 11/25/2022] Open
Abstract
Bacteria are often attached to surfaces in natural ecosystems. A surface-associated lifestyle can have advantages, but shifts in the physiochemical state of the environment may result in conditions in which attachment has a negative fitness impact. Therefore, bacteria employ numerous mechanisms to control the transition from an unattached to a sessile state. The Caulobacter crescentus protein HfiA is a potent developmental inhibitor of the secreted polysaccharide adhesin known as the holdfast, which enables permanent attachment to surfaces. Multiple environmental cues influence expression of hfiA, but mechanisms of hfiA regulation remain largely undefined. Through a forward genetic selection, we have discovered a multi-gene network encoding a suite of two-component system (TCS) proteins and transcription factors that coordinately control hfiA transcription, holdfast development and surface adhesion. The hybrid HWE-family histidine kinase, SkaH, is central among these regulators and forms heteromeric complexes with the kinases, LovK and SpdS. The response regulator SpdR indirectly inhibits hfiA expression by activating two XRE-family transcription factors that directly bind the hfiA promoter to repress its transcription. This study provides evidence for a model in which a consortium of environmental sensors and transcriptional regulators integrate environmental cues at the hfiA promoter to control the attachment decision. Living on a surface within a community of cells confers a number of advantages to a bacterium. However, the transition from a free-living, planktonic state to a surface-attached lifestyle should be tightly regulated to ensure that cells avoid adhering to toxic or resource-limited niches. Many bacteria build adhesive structures on the surface of their cell envelopes that enable attachment. We sought to discover genes that control development of the Caulobacter crescentus surface adhesin known as the holdfast. Our studies uncovered a network of signal transduction proteins that coordinately control the biosynthesis of the holdfast by regulating transcription of the holdfast inhibitor, hfiA. We conclude that C. crescentus uses a multi-component regulatory system to sense and integrate environmental information to determine whether to attach to a surface, or to remain in an unattached state.
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Affiliation(s)
- Leila M Reyes Ruiz
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Aretha Fiebig
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois United States of America
| | - Sean Crosson
- Committee on Genetics, Genomics and Systems Biology, University of Chicago, Chicago, Illinois, United States of America.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois United States of America.,Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
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15
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Narayanan S, Kumar L, Radhakrishnan SK. Sensory domain of the cell cycle kinase CckA regulates the differential DNA binding of the master regulator CtrA in Caulobacter crescentus. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:952-961. [PMID: 30496040 PMCID: PMC6169604 DOI: 10.1016/j.bbagrm.2018.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/28/2018] [Accepted: 08/28/2018] [Indexed: 01/20/2023]
Abstract
Sophisticated signaling mechanisms allow bacterial cells to cope with environmental and intracellular challenges. Activation of specific pathways ameliorates these challenges and thereby warrants integrity. Here, we demonstrate the pliability of the CckA-CtrA two-component signaling system in the freshwater bacterium Caulobacter crescentus. Our forward genetic screen to analyze suppressor mutations that can negate the chromosome segregation block induced by the topoisomerase IV inhibitor, NstA, yielded various point mutations in the cell cycle histidine kinase, CckA. Notably, we identified a point mutation in the PAS-B domain of CckA, which resulted in increased levels of phosphorylated CtrA (CtrA~P), the master cell cycle regulator. Surprisingly, this increase in CtrA~P levels did not translate into a genome-wide increase in the DNA occupancy of CtrA, but specifically enriched its affinity for the chromosomal origin of replication, Cori, and for a very small sub-set of CtrA regulated promoters. We show that through this enhanced binding of CtrA to the Cori, cells are able to overcome the toxic defects rendered by stable NstA through a possible slow down in the chromosome replication cycle. Taken together, our work opens up an unexplored and intriguing aspect of the CckA-CtrA signal transduction pathway. The distinctive DNA binding nature of CtrA and its regulation by CckA might also be crucial for pathogenesis because of the highly conserved nature of the CckA-CtrA pathway in alphaproteobacteria.
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Affiliation(s)
- Sharath Narayanan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India
| | - Lokesh Kumar
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India
| | - Sunish Kumar Radhakrishnan
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram 695551, Kerala, India.
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16
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Mouammine A, Collier J. The impact of DNA methylation in Alphaproteobacteria. Mol Microbiol 2018; 110:1-10. [PMID: 29995343 DOI: 10.1111/mmi.14079] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2018] [Indexed: 02/02/2023]
Abstract
Alphaproteobacteria include bacteria with very different modes of life, from free-living to host-associated and pathogenic bacteria. Their genomes vary in size and organization from single circular chromosomes to multipartite genomes and are often methylated by one or more adenine or cytosine methyltransferases (MTases). These include MTases that are part of restriction/modification systems and so-called orphan MTases. The development of novel technologies accelerated the analysis of methylomes and revealed the existence of epigenetic patterns in several Alphaproteobacteria. This review describes the known functions of DNA methylation in Alphaproteobacteria and also discusses its potential drawbacks through the accidental deamination of methylated cytosines. Particular emphasis is given to the strong connection between the cell cycle-regulated orphan MTase CcrM and the complex network that controls gene expression and cell cycle progression in Alphaproteobacteria.
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Affiliation(s)
- Annabelle Mouammine
- Faculty of Biology and Medicine, Department of Fundamental Microbiology, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland
| | - Justine Collier
- Faculty of Biology and Medicine, Department of Fundamental Microbiology, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland
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17
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Collier J. Cell division control in Caulobacter crescentus. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1862:685-690. [PMID: 29715525 DOI: 10.1016/j.bbagrm.2018.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/31/2022]
Abstract
Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this bacterium to control the levels of cell division proteins, their organization inside the cell and their activity as a function of the cell cycle. Strikingly, C. crescentus makes frequent use of master transcriptional regulators and epigenetic signals, most likely to synchronize cell division with other events of the cell cycle. In addition, cellular metabolism and DNA damage sensors emerge as central players regulating cell division in response to changing environmental conditions.
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Affiliation(s)
- Justine Collier
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Quartier UNIL/Sorge, Lausanne, CH 1015, Switzerland.
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18
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Goemans CV, Beaufay F, Wahni K, Van Molle I, Messens J, Collet JF. An essential thioredoxin is involved in the control of the cell cycle in the bacterium Caulobacter crescentus. J Biol Chem 2018; 293:3839-3848. [PMID: 29367337 PMCID: PMC5846133 DOI: 10.1074/jbc.ra117.001042] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/23/2018] [Indexed: 11/06/2022] Open
Abstract
Thioredoxins (Trxs) are antioxidant proteins that are conserved among all species. These proteins have been extensively studied and perform reducing reactions on a broad range of substrates. Here, we identified Caulobacter crescentus Trx1 (CCNA_03653; CcTrx1) as an oxidoreductase that is involved in the cell cycle progression of this model bacterium and is required to sustain life. Intriguingly, the abundance of CcTrx1 varies throughout the C. crescentus cell cycle: although the expression of CcTrx1 is induced in stalked cells, right before DNA replication initiation, CcTrx1 is actively degraded by the ClpXP protease in predivisional cells. Importantly, we demonstrated that regulation of the abundance of CcTrx1 is crucial for cell growth and survival as modulating CcTrx1 levels leads to cell death. Finally, we also report a comprehensive biochemical and structural characterization of this unique and essential Trx. The requirement to precisely control the abundance of CcTrx1 for cell survival underlines the importance of redox control for optimal cell cycle progression in C. crescentus.
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Affiliation(s)
- Camille V Goemans
- From WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium,
- the de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
- the Brussels Center for Redox Biology, 1200 Brussels, Belgium
| | - François Beaufay
- the de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Khadija Wahni
- the Brussels Center for Redox Biology, 1200 Brussels, Belgium
- the Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), 1050 Brussels, Belgium, and
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Inge Van Molle
- the Brussels Center for Redox Biology, 1200 Brussels, Belgium
- the Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), 1050 Brussels, Belgium, and
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Joris Messens
- the Brussels Center for Redox Biology, 1200 Brussels, Belgium
- the Center for Structural Biology, Vlaams Instituut voor Biotechnologie (VIB), 1050 Brussels, Belgium, and
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Jean-François Collet
- From WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium,
- the de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
- the Brussels Center for Redox Biology, 1200 Brussels, Belgium
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19
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Sporer AJ, Kahl LJ, Price-Whelan A, Dietrich LE. Redox-Based Regulation of Bacterial Development and Behavior. Annu Rev Biochem 2017; 86:777-797. [DOI: 10.1146/annurev-biochem-061516-044453] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Abigail J. Sporer
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Lisa J. Kahl
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Alexa Price-Whelan
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Lars E.P. Dietrich
- Department of Biological Sciences, Columbia University, New York, NY 10027
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20
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Hallez R. [Metabolism and cell cycle, two interconnected processes in bacteria]. Med Sci (Paris) 2016; 32:843-848. [PMID: 27758748 DOI: 10.1051/medsci/20163210017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To increase chances for a cell to survive in its natural environment, metabolism and cell cycle necessarily have to be interconnected. Indeed, cells need, on the one hand, to check their metabolic status before initiating a cell cycle step often energy-consuming, and, on the other hand, to complete some cell cycle steps before modifying their metabolism. Because bacteria do not differ from the rules, an increasing number of examples of connection between metabolism and cell cycle emerged these last years. Identifying metabolic enzymes as messengers coordinating metabolism and cell cycle allows the addition of another dimension to metabolic maps. Likewise, the very high conservation of these metabolic maps, from bacteria to human, allows inspiring research on tumor cells that are known to have an unrestrained cell cycle and a voracious appetite.
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Affiliation(s)
- Régis Hallez
- Bacterial Cell cycle and Development (BCcD), unité de recherche en biologie des micro-organismes (URBM), université de Namur (UNamur), 61 rue de Bruxelles, 5000 Namur, Belgique
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21
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In-phase oscillation of global regulons is orchestrated by a pole-specific organizer. Proc Natl Acad Sci U S A 2016; 113:12550-12555. [PMID: 27791133 PMCID: PMC5098664 DOI: 10.1073/pnas.1610723113] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell fate determination in the asymmetric bacterium Caulobacter crescentus (Caulobacter) is triggered by the localization of the developmental regulator SpmX to the old (stalked) cell pole during the G1→S transition. Although SpmX is required to localize and activate the cell fate-determining kinase DivJ at the stalked pole in Caulobacter, in cousins such as Asticcacaulis, SpmX directs organelle (stalk) positioning and possibly other functions. We define the conserved σ54-dependent transcriptional activator TacA as a global regulator in Caulobacter whose activation by phosphorylation is indirectly down-regulated by SpmX. Using a combination of forward genetics and cytological screening, we uncover a previously uncharacterized and polarized component (SpmY) of the TacA phosphorylation control system, and we show that SpmY function and localization are conserved. Thus, SpmX organizes a site-specific, ancestral, and multifunctional regulatory hub integrating the in-phase oscillation of two global transcriptional regulators, CtrA (the master cell cycle transcriptional regulator A) and TacA, that perform important cell cycle functions.
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Abstract
Protein degradation is essential for all living things. Bacteria use energy-dependent proteases to control protein destruction in a highly specific manner. Recognition of substrates is determined by the inherent specificity of the proteases and through adaptor proteins that alter the spectrum of substrates. In the α-proteobacterium Caulobacter crescentus, regulated protein degradation is required for stress responses, developmental transitions, and cell cycle progression. In this review, we describe recent progress in our understanding of the regulated and stress-responsive protein degradation pathways in Caulobacter. We discuss how organization of highly specific adaptors into functional hierarchies drives destruction of proteins during the bacterial cell cycle. Because all cells must balance the need for degradation of many true substrates with the toxic consequences of nonspecific protein destruction, principles found in one system likely generalize to others.
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Affiliation(s)
| | - Peter Chien
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003;
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VAP, a Versatile Access Point for the Endoplasmic Reticulum: Review and analysis of FFAT-like motifs in the VAPome. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:952-961. [PMID: 26898182 DOI: 10.1016/j.bbalip.2016.02.009] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 02/12/2016] [Accepted: 02/12/2016] [Indexed: 11/24/2022]
Abstract
Dysfunction of VAMP-associated protein (VAP) is associated with neurodegeneration, both Amyotrophic Lateral Sclerosis and Parkinson's disease. Here we summarize what is known about the intracellular interactions of VAP in humans and model organisms. VAP is a simple, small and highly conserved protein on the cytoplasmic face of the endoplasmic reticulum (ER). It is the sole protein on that large organelle that acts as a receptor for cytoplasmic proteins. This may explain the extremely wide range of interacting partners of VAP, with components of many cellular pathways binding it to access the ER. Many proteins that bind VAP also target other intracellular membranes, so VAP is a component of multiple molecular bridges at membrane contact sites between the ER and other organelles. So far approximately 100 proteins have been identified in the VAP interactome (VAPome), of which a small minority have a "two phenylalanines in an acidic tract" (FFAT) motif as it was originally defined. We have analyzed the entire VAPome in humans and yeast using a simple algorithm that identifies many more FFAT-like motifs. We show that approximately 50% of the VAPome binds directly or indirectly via the VAP-FFAT interaction. We also review evidence on pathogenesis in genetic disorders of VAP, which appear to arise from reduced overall VAP levels, leading to ER stress. It is not possible to identify one single interaction that underlies disease. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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