| Autor: |
Bunduc CM; Centre for Structural Systems Biology, Hamburg, Germany.; Institute of Structural and Systems Biology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.; Deutsches Elektron Synchrotron DESY, Hamburg, Germany.; Molecular Microbiology Section, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands., Fahrenkamp D; Centre for Structural Systems Biology, Hamburg, Germany.; Institute of Structural and Systems Biology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.; Deutsches Elektron Synchrotron DESY, Hamburg, Germany., Wald J; Centre for Structural Systems Biology, Hamburg, Germany.; Institute of Structural and Systems Biology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.; Deutsches Elektron Synchrotron DESY, Hamburg, Germany., Ummels R; Department of Medical Microbiology and Infection Control, Amsterdam Infection and Immunity Institute, Amsterdam UMC, Amsterdam, The Netherlands., Bitter W; Molecular Microbiology Section, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.; Department of Medical Microbiology and Infection Control, Amsterdam Infection and Immunity Institute, Amsterdam UMC, Amsterdam, The Netherlands., Houben ENG; Molecular Microbiology Section, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands., Marlovits TC; Centre for Structural Systems Biology, Hamburg, Germany. marlovits@marlovitslab.org.; Institute of Structural and Systems Biology, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. marlovits@marlovitslab.org.; Deutsches Elektron Synchrotron DESY, Hamburg, Germany. marlovits@marlovitslab.org. |
| Abstrakt: |
Mycobacterium tuberculosis is the cause of one of the most important infectious diseases in humans, which leads to 1.4 million deaths every year 1 . Specialized protein transport systems-known as type VII secretion systems (T7SSs)-are central to the virulence of this pathogen, and are also crucial for nutrient and metabolite transport across the mycobacterial cell envelope 2,3 . Here we present the structure of an intact T7SS inner-membrane complex of M. tuberculosis. We show how the 2.32-MDa ESX-5 assembly, which contains 165 transmembrane helices, is restructured and stabilized as a trimer of dimers by the MycP 5 protease. A trimer of MycP 5 caps a central periplasmic dome-like chamber that is formed by three EccB 5 dimers, with the proteolytic sites of MycP 5 facing towards the cavity. This chamber suggests a central secretion and processing conduit. Complexes without MycP 5 show disruption of the EccB 5 periplasmic assembly and increased flexibility, which highlights the importance of MycP 5 for complex integrity. Beneath the EccB 5 -MycP 5 chamber, dimers of the EccC 5 ATPase assemble into three bundles of four transmembrane helices each, which together seal the potential central secretion channel. Individual cytoplasmic EccC 5 domains adopt two distinctive conformations that probably reflect different secretion states. Our work suggests a previously undescribed mechanism of protein transport and provides a structural scaffold to aid in the development of drugs against this major human pathogen. |
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