Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems
ABSTRACT Prokaryotes use type IV secretion systems (T4SSs) to translocate substrates (e.g., nucleoprotein, DNA, and protein) and/or elaborate surface structures (i.e., pili or adhesins). Bacterial genomes may encode multiple T4SSs, e.g., there are three functionally divergent T4SSs in some Bartonell...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Society for Microbiology
2015-12-01
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| Series: | mBio |
| Online Access: | https://journals.asm.org/doi/10.1128/mBio.01867-15 |
| _version_ | 1818431693483147264 |
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| author | Joseph J. Gillespie Isabelle Q. H. Phan Holger Scheib Sandhya Subramanian Thomas E. Edwards Stephanie S. Lehman Hanna Piitulainen M. Sayeedur Rahman Kristen E. Rennoll-Bankert Bart L. Staker Suvi Taira Robin Stacy Peter J. Myler Abdu F. Azad Arto T. Pulliainen |
| author_facet | Joseph J. Gillespie Isabelle Q. H. Phan Holger Scheib Sandhya Subramanian Thomas E. Edwards Stephanie S. Lehman Hanna Piitulainen M. Sayeedur Rahman Kristen E. Rennoll-Bankert Bart L. Staker Suvi Taira Robin Stacy Peter J. Myler Abdu F. Azad Arto T. Pulliainen |
| author_sort | Joseph J. Gillespie |
| collection | DOAJ |
| description | ABSTRACT Prokaryotes use type IV secretion systems (T4SSs) to translocate substrates (e.g., nucleoprotein, DNA, and protein) and/or elaborate surface structures (i.e., pili or adhesins). Bacterial genomes may encode multiple T4SSs, e.g., there are three functionally divergent T4SSs in some Bartonella species (vir, vbh, and trw). In a unique case, most rickettsial species encode a T4SS (rvh) enriched with gene duplication. Within single genomes, the evolutionary and functional implications of cross-system interchangeability of analogous T4SS protein components remains poorly understood. To lend insight into cross-system interchangeability, we analyzed the VirB8 family of T4SS channel proteins. Crystal structures of three VirB8 and two TrwG Bartonella proteins revealed highly conserved C-terminal periplasmic domain folds and dimerization interfaces, despite tremendous sequence divergence. This implies remarkable structural constraints for VirB8 components in the assembly of a functional T4SS. VirB8/TrwG heterodimers, determined via bacterial two-hybrid assays and molecular modeling, indicate that differential expression of trw and vir systems is the likely barrier to VirB8-TrwG interchangeability. We also determined the crystal structure of Rickettsia typhi RvhB8-II and modeled its coexpressed divergent paralog RvhB8-I. Remarkably, while RvhB8-I dimerizes and is structurally similar to other VirB8 proteins, the RvhB8-II dimer interface deviates substantially from other VirB8 structures, potentially preventing RvhB8-I/RvhB8-II heterodimerization. For the rvh T4SS, the evolution of divergent VirB8 paralogs implies a functional diversification that is unknown in other T4SSs. Collectively, our data identify two different constraints (spatiotemporal for Bartonella trw and vir T4SSs and structural for rvh T4SSs) that mediate the functionality of multiple divergent T4SSs within a single bacterium. IMPORTANCE Assembly of multiprotein complexes at the right time and at the right cellular location is a fundamentally important task for any organism. In this respect, bacteria that express multiple analogous type IV secretion systems (T4SSs), each composed of around 12 different components, face an overwhelming complexity. Our work here presents the first structural investigation on factors regulating the maintenance of multiple T4SSs within a single bacterium. The structural data imply that the T4SS-expressing bacteria rely on two strategies to prevent cross-system interchangeability: (i) tight temporal regulation of expression or (ii) rapid diversification of the T4SS components. T4SSs are ideal drug targets provided that no analogous counterparts are known from eukaryotes. Drugs targeting the barriers to cross-system interchangeability (i.e., regulators) could dysregulate the structural and functional independence of discrete systems, potentially creating interference that prevents their efficient coordination throughout bacterial infection. |
| first_indexed | 2024-12-14T15:53:22Z |
| format | Article |
| id | doaj.art-eddba446b9474c58833850283358d59e |
| institution | Directory Open Access Journal |
| issn | 2150-7511 |
| language | English |
| last_indexed | 2024-12-14T15:53:22Z |
| publishDate | 2015-12-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj.art-eddba446b9474c58833850283358d59e2022-12-21T22:55:18ZengAmerican Society for MicrobiologymBio2150-75112015-12-016610.1128/mBio.01867-15Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion SystemsJoseph J. Gillespie0Isabelle Q. H. Phan1Holger Scheib2Sandhya Subramanian3Thomas E. Edwards4Stephanie S. Lehman5Hanna Piitulainen6M. Sayeedur Rahman7Kristen E. Rennoll-Bankert8Bart L. Staker9Suvi Taira10Robin Stacy11Peter J. Myler12Abdu F. Azad13Arto T. Pulliainen14Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USASeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USAVenom Evolution Lab, School of Biological Sciences, University of Queensland, St. Lucia, Queensland, AustraliaSeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USASeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USADepartment of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USADepartment of Biosciences, University of Helsinki, Helsinki, FinlandDepartment of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USADepartment of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USASeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USADepartment of Biosciences, University of Helsinki, Helsinki, FinlandSeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USASeattle Structural Genomics Center for Infectious Disease, Seattle, Washington, USADepartment of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USADepartment of Biosciences, University of Helsinki, Helsinki, FinlandABSTRACT Prokaryotes use type IV secretion systems (T4SSs) to translocate substrates (e.g., nucleoprotein, DNA, and protein) and/or elaborate surface structures (i.e., pili or adhesins). Bacterial genomes may encode multiple T4SSs, e.g., there are three functionally divergent T4SSs in some Bartonella species (vir, vbh, and trw). In a unique case, most rickettsial species encode a T4SS (rvh) enriched with gene duplication. Within single genomes, the evolutionary and functional implications of cross-system interchangeability of analogous T4SS protein components remains poorly understood. To lend insight into cross-system interchangeability, we analyzed the VirB8 family of T4SS channel proteins. Crystal structures of three VirB8 and two TrwG Bartonella proteins revealed highly conserved C-terminal periplasmic domain folds and dimerization interfaces, despite tremendous sequence divergence. This implies remarkable structural constraints for VirB8 components in the assembly of a functional T4SS. VirB8/TrwG heterodimers, determined via bacterial two-hybrid assays and molecular modeling, indicate that differential expression of trw and vir systems is the likely barrier to VirB8-TrwG interchangeability. We also determined the crystal structure of Rickettsia typhi RvhB8-II and modeled its coexpressed divergent paralog RvhB8-I. Remarkably, while RvhB8-I dimerizes and is structurally similar to other VirB8 proteins, the RvhB8-II dimer interface deviates substantially from other VirB8 structures, potentially preventing RvhB8-I/RvhB8-II heterodimerization. For the rvh T4SS, the evolution of divergent VirB8 paralogs implies a functional diversification that is unknown in other T4SSs. Collectively, our data identify two different constraints (spatiotemporal for Bartonella trw and vir T4SSs and structural for rvh T4SSs) that mediate the functionality of multiple divergent T4SSs within a single bacterium. IMPORTANCE Assembly of multiprotein complexes at the right time and at the right cellular location is a fundamentally important task for any organism. In this respect, bacteria that express multiple analogous type IV secretion systems (T4SSs), each composed of around 12 different components, face an overwhelming complexity. Our work here presents the first structural investigation on factors regulating the maintenance of multiple T4SSs within a single bacterium. The structural data imply that the T4SS-expressing bacteria rely on two strategies to prevent cross-system interchangeability: (i) tight temporal regulation of expression or (ii) rapid diversification of the T4SS components. T4SSs are ideal drug targets provided that no analogous counterparts are known from eukaryotes. Drugs targeting the barriers to cross-system interchangeability (i.e., regulators) could dysregulate the structural and functional independence of discrete systems, potentially creating interference that prevents their efficient coordination throughout bacterial infection.https://journals.asm.org/doi/10.1128/mBio.01867-15 |
| spellingShingle | Joseph J. Gillespie Isabelle Q. H. Phan Holger Scheib Sandhya Subramanian Thomas E. Edwards Stephanie S. Lehman Hanna Piitulainen M. Sayeedur Rahman Kristen E. Rennoll-Bankert Bart L. Staker Suvi Taira Robin Stacy Peter J. Myler Abdu F. Azad Arto T. Pulliainen Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems mBio |
| title | Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems |
| title_full | Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems |
| title_fullStr | Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems |
| title_full_unstemmed | Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems |
| title_short | Structural Insight into How Bacteria Prevent Interference between Multiple Divergent Type IV Secretion Systems |
| title_sort | structural insight into how bacteria prevent interference between multiple divergent type iv secretion systems |
| url | https://journals.asm.org/doi/10.1128/mBio.01867-15 |
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