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Alakavuklar MA, Fiebig A, Crosson S. The Brucella Cell Envelope. Annu Rev Microbiol 2023; 77:233-253. [PMID: 37104660 PMCID: PMC10787603 DOI: 10.1146/annurev-micro-032521-013159] [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] [Indexed: 04/29/2023]
Abstract
The cell envelope is a multilayered structure that insulates the interior of bacterial cells from an often chaotic outside world. Common features define the envelope across the bacterial kingdom, but the molecular mechanisms by which cells build and regulate this critical barrier are diverse and reflect the evolutionary histories of bacterial lineages. Intracellular pathogens of the genus Brucella exhibit marked differences in cell envelope structure, regulation, and biogenesis when compared to more commonly studied gram-negative bacteria and therefore provide an excellent comparative model for study of the gram-negative envelope. We review distinct features of the Brucella envelope, highlighting a conserved regulatory system that links cell cycle progression to envelope biogenesis and cell division. We further discuss recently discovered structural features of the Brucella envelope that ensure envelope integrity and that facilitate cell survival in the face of host immune stressors.
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Affiliation(s)
- Melene A Alakavuklar
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
| | - Aretha Fiebig
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
| | - Sean Crosson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
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Hill JH, Massaquoi MS, Sweeney EG, Wall ES, Jahl P, Bell R, Kallio K, Derrick D, Murtaugh LC, Parthasarathy R, Remington SJ, Round JL, Guillemin K. BefA, a microbiota-secreted membrane disrupter, disseminates to the pancreas and increases β cell mass. Cell Metab 2022; 34:1779-1791.e9. [PMID: 36240759 PMCID: PMC9633563 DOI: 10.1016/j.cmet.2022.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/26/2022] [Accepted: 08/31/2022] [Indexed: 01/11/2023]
Abstract
Microbiome dysbiosis is a feature of diabetes, but how microbial products influence insulin production is poorly understood. We report the mechanism of BefA, a microbiome-derived protein that increases proliferation of insulin-producing β cells during development in gnotobiotic zebrafish and mice. BefA disseminates systemically by multiple anatomic routes to act directly on pancreatic islets. We detail BefA's atomic structure, containing a lipid-binding SYLF domain, and demonstrate that it permeabilizes synthetic liposomes and bacterial membranes. A BefA mutant impaired in membrane disruption fails to expand β cells, whereas the pore-forming host defense protein, Reg3, stimulates β cell proliferation. Our work demonstrates that membrane permeabilization by microbiome-derived and host defense proteins is necessary and sufficient for β cell expansion during pancreas development, potentially connecting microbiome composition with diabetes risk.
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Affiliation(s)
- Jennifer Hampton Hill
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Department of Pathology, Division of Microbiology and Immunology, University of Utah, Salt Lake City, UT 84112, USA
| | | | | | - Elena S Wall
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Philip Jahl
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
| | - Rickesha Bell
- Department of Pathology, Division of Microbiology and Immunology, University of Utah, Salt Lake City, UT 84112, USA
| | - Karen Kallio
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Daniel Derrick
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - L Charles Murtaugh
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Raghuveer Parthasarathy
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
| | - S James Remington
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - June L Round
- Department of Pathology, Division of Microbiology and Immunology, University of Utah, Salt Lake City, UT 84112, USA
| | - Karen Guillemin
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA; Humans and the Microbiome Program, Canadian Institute for Advanced Research, Toronto, ON M5G 1Z8, Canada.
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