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Demey LM, Sinha R, DiRita VJ. An essential host dietary fatty acid promotes TcpH inhibition of TcpP proteolysis promoting virulence gene expression in Vibrio cholerae. mBio 2024; 15:e0072124. [PMID: 38958446 PMCID: PMC11323476 DOI: 10.1128/mbio.00721-24] [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: 04/11/2024] [Accepted: 05/03/2024] [Indexed: 07/04/2024] Open
Abstract
Vibrio cholerae is a Gram-negative gastrointestinal pathogen responsible for the diarrheal disease cholera. Expression of key virulence factors, cholera toxin and toxin-coregulated pilus, is regulated directly by ToxT and indirectly by two transmembrane transcription regulators (TTRs), ToxR and TcpP, that promote the expression of toxT. TcpP abundance and activity are controlled by TcpH, a single-pass transmembrane protein, which protects TcpP from a two-step proteolytic process known as regulated intramembrane proteolysis (RIP). The mechanism of TcpH-mediated protection of TcpP represents a major gap in our understanding of V. cholerae pathogenesis. The absence of tcpH leads to unimpeded degradation of TcpP in vitro and a colonization defect in a neonate mouse model of V. cholerae colonization. Here, we show that TcpH protects TcpP from RIP via direct interaction. We also demonstrate that α-linolenic acid, a dietary fatty acid, promotes TcpH-dependent inhibition of RIP via co-association of TcpP and TcpH molecules within detergent-resistant membranes (DRMs) in a mechanism requiring the TcpH transmembrane domain. Taken together, our data support a model where V. cholerae cells use exogenous α-linolenic acid to remodel the phospholipid bilayer in vivo, leading to co-association of TcpP and TcpH within DRMs where RIP of TcpP is inhibited by TcpH, thereby promoting V. cholerae pathogenicity. IMPORTANCE Vibrio cholerae continues to pose a significant global burden on health and an alternative therapeutic approach is needed, due to evolving multidrug resistance strains. Transcription of toxT, stimulated by TcpP and ToxR, is essential for V. cholerae pathogenesis. Our results show that TcpP, one of the major regulators of toxT gene expression, is protected from proteolysis by TcpH, via direct interaction. Furthermore, we identified a gut metabolite, α-linolenic acid, that stimulates the co-association of TcpP and TcpH within detergent-resistant membranes (also known as lipid-ordered membrane domains), thereby supporting TcpH-dependent antagonism of TcpP proteolysis. Data presented here extend our knowledge of RIP, virulence gene regulation in V. cholerae, and, to the best of our knowledge, provides the first evidence that lipid-ordered membranes exist within V. cholerae. The model presented here also suggests that TTRs, common among bacteria and archaea, and co-component signal transduction systems present in Enterobacteria, could also be influenced similarly.
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Affiliation(s)
- Lucas M. Demey
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Ritam Sinha
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Victor J. DiRita
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
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Achimovich AM, Yan T, Gahlmann A. Dimerization of iLID optogenetic proteins observed using 3D single-molecule tracking in live E. coli. Biophys J 2023; 122:3254-3267. [PMID: 37421134 PMCID: PMC10465707 DOI: 10.1016/j.bpj.2023.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 01/25/2023] [Accepted: 07/05/2023] [Indexed: 07/09/2023] Open
Abstract
3D single-molecule tracking microscopy has enabled measurements of protein diffusion in living cells, offering information about protein dynamics and cellular environments. For example, different diffusive states can be resolved and assigned to protein complexes of different size and composition. However, substantial statistical power and biological validation, often through genetic deletion of binding partners, are required to support diffusive state assignments. When investigating cellular processes, real-time perturbations to protein spatial distributions is preferable to permanent genetic deletion of an essential protein. For example, optogenetic dimerization systems can be used to manipulate protein spatial distributions that could offer a means to deplete specific diffusive states observed in single-molecule tracking experiments. Here, we evaluate the performance of the iLID optogenetic system in living E. coli cells using diffraction-limited microscopy and 3D single-molecule tracking. We observed a robust optogenetic response in protein spatial distributions after 488 nm laser activation. Surprisingly, 3D single-molecule tracking results indicate activation of the optogenetic response when illuminating with high-intensity light with wavelengths at which there is minimal photon absorbance by the LOV2 domain. The preactivation can be minimized through the use of iLID system mutants, and titration of protein expression levels.
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Affiliation(s)
- Alecia M Achimovich
- Department of Molecular Physiology & Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Ting Yan
- Department of Chemistry, University of Virginia, Charlottesville, Virginia
| | - Andreas Gahlmann
- Department of Molecular Physiology & Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia; Department of Chemistry, University of Virginia, Charlottesville, Virginia.
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3
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Prindle JR, de Cuba OIC, Gahlmann A. Single-molecule tracking to determine the abundances and stoichiometries of freely-diffusing protein complexes in living cells: Past applications and future prospects. J Chem Phys 2023; 159:071002. [PMID: 37589409 PMCID: PMC10908566 DOI: 10.1063/5.0155638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/06/2023] [Indexed: 08/18/2023] Open
Abstract
Most biological processes in living cells rely on interactions between proteins. Live-cell compatible approaches that can quantify to what extent a given protein participates in homo- and hetero-oligomeric complexes of different size and subunit composition are therefore critical to advance our understanding of how cellular physiology is governed by these molecular interactions. Biomolecular complex formation changes the diffusion coefficient of constituent proteins, and these changes can be measured using fluorescence microscopy-based approaches, such as single-molecule tracking, fluorescence correlation spectroscopy, and fluorescence recovery after photobleaching. In this review, we focus on the use of single-molecule tracking to identify, resolve, and quantify the presence of freely-diffusing proteins and protein complexes in living cells. We compare and contrast different data analysis methods that are currently employed in the field and discuss experimental designs that can aid the interpretation of the obtained results. Comparisons of diffusion rates for different proteins and protein complexes in intracellular aqueous environments reported in the recent literature reveal a clear and systematic deviation from the Stokes-Einstein diffusion theory. While a complete and quantitative theoretical explanation of why such deviations manifest is missing, the available data suggest the possibility of weighing freely-diffusing proteins and protein complexes in living cells by measuring their diffusion coefficients. Mapping individual diffusive states to protein complexes of defined molecular weight, subunit stoichiometry, and structure promises to provide key new insights into how protein-protein interactions regulate protein conformational, translational, and rotational dynamics, and ultimately protein function.
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Affiliation(s)
- Joshua Robert Prindle
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Olivia Isabella Christiane de Cuba
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, USA
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Canals A, Pieretti S, Muriel-Masanes M, El Yaman N, Plecha SC, Thomson JJ, Fàbrega-Ferrer M, Pérez-Luque R, Krukonis ES, Coll M. ToxR activates the Vibrio cholerae virulence genes by tethering DNA to the membrane through versatile binding to multiple sites. Proc Natl Acad Sci U S A 2023; 120:e2304378120. [PMID: 37428913 PMCID: PMC10629549 DOI: 10.1073/pnas.2304378120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/31/2023] [Indexed: 07/12/2023] Open
Abstract
ToxR, a Vibrio cholerae transmembrane one-component signal transduction factor, lies within a regulatory cascade that results in the expression of ToxT, toxin coregulated pilus, and cholera toxin. While ToxR has been extensively studied for its ability to activate or repress various genes in V. cholerae, here we present the crystal structures of the ToxR cytoplasmic domain bound to DNA at the toxT and ompU promoters. The structures confirm some predicted interactions, yet reveal other unexpected promoter interactions with implications for other potential regulatory roles for ToxR. We show that ToxR is a versatile virulence regulator that recognizes diverse and extensive, eukaryotic-like regulatory DNA sequences, that relies more on DNA structural elements than specific sequences for binding. Using this topological DNA recognition mechanism, ToxR can bind both in tandem and in a twofold inverted-repeat-driven manner. Its regulatory action is based on coordinated multiple binding to promoter regions near the transcription start site, which can remove the repressing H-NS proteins and prepares the DNA for optimal interaction with the RNA polymerase.
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Affiliation(s)
- Albert Canals
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
| | - Simone Pieretti
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
| | - Mireia Muriel-Masanes
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
| | - Nour El Yaman
- Department of Biology, University of Detroit Mercy, Detroit, MI48221
| | - Sarah C. Plecha
- Division of Integrated Biomedical Sciences, University of Detroit Mercy School of Dentistry, Detroit, MI48208
| | - Joshua J. Thomson
- Division of Integrated Biomedical Sciences, University of Detroit Mercy School of Dentistry, Detroit, MI48208
| | - Montserrat Fàbrega-Ferrer
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
| | - Rosa Pérez-Luque
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
| | - Eric S. Krukonis
- Division of Integrated Biomedical Sciences, University of Detroit Mercy School of Dentistry, Detroit, MI48208
| | - Miquel Coll
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028Barcelona, Spain
- Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, 08028Barcelona, Spain
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5
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Calkins AL, Demey LM, Rosenthal BM, DiRita VJ, Biteen JS. Achieving Single-Molecule Tracking of Subcellular Regulation in Bacteria during Real-Time Environmental Perturbations. Anal Chem 2023; 95:774-783. [PMID: 36576807 DOI: 10.1021/acs.analchem.2c02899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacteria rely on protein systems for regulation in response to external environmental signals. Single-molecule fluorescence imaging and tracking has elucidated the complex mechanism of these protein systems in a variety of bacteria. We recently investigated Vibrio cholerae, the Gram-negative bacterium responsible for the human cholera disease, and its regulation of the production of toxins and virulence factors through the membrane-localized transcription factors TcpP and ToxR. These experiments determined that TcpP and ToxR work cooperatively under steady-state conditions, but measurements of how these dynamical interactions change over the course of environmental perturbations were precluded by the traditional preparation of bacterial cells confined on agarose pads. Here, we address this gap in technology and access single-molecule dynamics during real-time changes by implementing two alternative sample preparations: microfluidic devices and chitosan-coated coverslips. We report the first demonstration of single-molecule tracking within live bacterial cells in a microfluidic device. Additionally, using the chitosan-coated coverslips, we show that real-time environmental changes impact TcpP-PAmCherry dynamics, activating a virulence condition in the bacteria about 45 min after dropping to pH 6 and about 20 min after inducing ToxR expression. These new technology advances open our ability for new experiments studying a variety of bacteria with single-molecule imaging and tracking during real-time environmental perturbations.
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Affiliation(s)
- Anna L Calkins
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48104, United States
| | - Lucas M Demey
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Brooke M Rosenthal
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48104, United States
| | - Victor J DiRita
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Julie S Biteen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48104, United States
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Wu J, Liu Y, Li W, Li F, Liu R, Sun H, Qin J, Feng X, Huang D, Liu B. MlrA, a MerR family regulator in Vibrio cholerae, senses the anaerobic signal in the small intestine of the host to promote bacterial intestinal colonization. Gut Microbes 2022; 14:2143216. [PMID: 36369865 PMCID: PMC9662190 DOI: 10.1080/19490976.2022.2143216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vibrio cholerae (V. cholerae), one of the most important bacterial pathogens in history, is a gram-negative motile bacterium that causes fatal pandemic disease in humans via oral ingestion of contaminated water or food. This process involves the coordinated actions of numerous regulatory factors. The MerR family regulators, which are widespread in prokaryotes, have been reported to be associated with pathogenicity. However, the role of the MerR family regulators in V. cholerae virulence remains unknown. Our study systematically investigated the influence of MerR family regulators on intestinal colonization of V. cholerae within the host. Among the five MerR family regulators, MlrA was found to significantly promote the colonization capacity of V. cholerae in infant mice. Furthermore, we revealed that MlrA increases bacterial intestinal colonization by directly enhancing the expression of tcpA, which encodes one of the most important virulence factors in V. cholerae, by binding to its promoter region. In addition, we revealed that during infection, mlrA is activated by anaerobic signals in the small intestine of the host through Fnr. In summary, our findings reveal a MlrA-mediated virulence regulation pathway that enables V. cholerae to sense environmental signals at the infection site to precisely activate virulence gene expression, thus providing useful insights into the pathogenic mechanisms of V. cholerae.
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Affiliation(s)
- Jialin Wu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Yutao Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China
| | - Wendi Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Fan Li
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Ruiying Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Hao Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Jingliang Qin
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Xiaohui Feng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Di Huang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China,Di Huang TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China,Nankai International Advanced Research Institute, Nankai University Shenzhen, China,CONTACT Bin Liu TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
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