Structural interactions define assembly adapter function of a type II secretion system pseudopilin.

Autor:	Escobar CA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA., Douzi B; Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille Université, Marseille, France., Ball G; Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille Université, Marseille, France., Barbat B; Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille Université, Marseille, France., Alphonse S; Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille Université, Marseille, France., Quinton L; Laboratory of Mass Spectrometry, MolSys Research Unit, University of Liège, Liège, Belgium. Electronic address: loic.quinton@uliege.be., Voulhoux R; Laboratoire de Chimie Bactérienne (UMR7283), Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille Université, Marseille, France. Electronic address: voulhoux@imm.cnrs.fr., Forest KT; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA. Electronic address: forest@bact.wisc.edu.
Jazyk:	angličtina
Zdroj:	Structure (London, England : 1993) [Structure] 2021 Oct 07; Vol. 29 (10), pp. 1116-1127.e8. Date of Electronic Publication: 2021 Jun 16.
DOI:	10.1016/j.str.2021.05.015
Abstrakt:	The type IV filament superfamily comprises widespread membrane-associated polymers in prokaryotes. The type II secretion system (T2SS), a virulence pathway in many pathogens, belongs to this superfamily. A knowledge gap in understanding of the T2SS is the molecular role of a small "pseudopilin" protein. Using multiple biophysical techniques, we have deciphered how this missing component of the Xcp T2SS architecture is structurally integrated, and thereby unlocked its function. We demonstrate that low-abundance XcpH is the adapter that bridges a trimeric initiating tip complex, XcpIJK, with a periplasmic filament of XcpG subunits. Each pseudopilin protein caps an XcpG protofilament in an overall pseudopilus compatible with dimensions of the periplasm and the outer membrane-spanning secretin through which substrates pass. Unexpectedly, to fulfill its adapter function, the XcpH N-terminal helix must be unwound, a property shared with XcpG subunits. We provide an experimentally validated three-dimensional structural model of a complete type IV filament. Competing Interests: Declaration of interests The authors declare no competing interests. (Copyright © 2021 Elsevier Ltd. All rights reserved.)
Databáze:	MEDLINE
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