Inner-membrane GspF of the bacterial type II secretion system is a dimeric adaptor mediating pseudopilus biogenesis

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Item Type:	Preprint
Title:	Inner-membrane GspF of the bacterial type II secretion system is a dimeric adaptor mediating pseudopilus biogenesis
Creators Name:	Van Putte, W., De Vos, T., Van Den Broeck, W., Stahlberg, H., Kudryashev, M. and Savvides, S.N.
Abstract:	The type II secretion system (T2SS), a protein complex spanning the bacterial envelope, is pivotal to bacterial pathogenicity. Central to T2SS function is the extrusion of protein cargos from the periplasm into the extracellular environment mediated by a pseudopilus and motorized by a cytosolic ATPase. GspF, an inner-membrane component of T2SS has long been considered to be a key player in this process, yet the structural basis of its role had remained elusive. Here, we employed single-particle electron microscopy based on XcpS (GspF) from the T2SS of pathogenic P. aeruginosa stabilized by a nanobody, to show that XcpS adopts a dimeric structure mediated by its transmembrane helices. This assembly matches in terms of overall organization and dimensions the basal inner-membrane cassette of a T2SS machinery. Thus, GspF is poised to serve as an adaptor involved in the mediation of propeller-like torque generated by the motor ATPase to the secretion pseudopilus.
Source:	bioRxiv
Publisher:	Cold Spring Harbor Laboratory Press
Article Number:	435982
Date:	5 October 2018
Official Publication:	https://doi.org/10.1101/435982

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