Structural and Functional Characterization of the Bacterial Type III Secretion Export Apparatus

PLoS Pathogens

Matthias J. Brunner¹  Charlotta Schärfe²  Patrizia Abrusci³  Thomas C. Marlovits⁴  Jun Yan⁵  Mirita Franz-Wachtel⁶  Carol V. Robinson⁶  Iwan Grin⁷  Boris Macek⁷  Jorge E. Galán⁸  Mehari Tesfazgi Mebrhatu⁸  Oliver Kohlbacher⁸  Tobias Dietsche⁸  Susann Zilkenat⁹  Samuel Wagner⁹  Susan Lea^1,10 

[1] Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE) and German Electron Synchrotron Centre (DESY), Hamburg, Germany;Department of Chemistry, University of Oxford, Oxford, United Kingdom;Institute of Molecular Biotechnology (IMBA), Vienna Biocenter (VBC), Vienna, Austria;Max Planck Institute for Developmental Biology, Biomolecular Interactions, Tübingen, Germany;Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria;Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom;University of Tübingen, Center for BioinformaticsTübingen, Germany;University of Tübingen, Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, Tübingen, Germany;University of Tübingen, Proteome Center Tübingen, Tübingen, Germany;Yale University School of Medicine, Department of Microbial Pathogenesis, New Haven, Connecticut, United States of America

关键词: Salmonella typhimurium;    Immunodetection;    Protein interactions;    Cross-linking;    SDS polyacrylamide gel electrophoresis;    Secretion;    Secretion systems;    Sequence alignment;   

DOI  :  10.1371/journal.ppat.1006071

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Bacterial type III protein secretion systems inject effector proteins into eukaryotic host cells in order to promote survival and colonization of Gram-negative pathogens and symbionts. Secretion across the bacterial cell envelope and injection into host cells is facilitated by a so-called injectisome. Its small hydrophobic export apparatus components SpaP and SpaR were shown to nucleate assembly of the needle complex and to form the central “cup” substructure of a Salmonella Typhimurium secretion system. However, the in vivo placement of these components in the needle complex and their function during the secretion process remained poorly defined. Here we present evidence that a SpaP pentamer forms a 15 Å wide pore and provide a detailed map of SpaP interactions with the export apparatus components SpaQ, SpaR, and SpaS. We further refine the current view of export apparatus assembly, consolidate transmembrane topology models for SpaP and SpaR, and present intimate interactions of the periplasmic domains of SpaP and SpaR with the inner rod protein PrgJ, indicating how export apparatus and needle filament are connected to create a continuous conduit for substrate translocation.

【 授权许可】

CC BY