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Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
Published on: December 17, 2013
Structure of the GspK-GspI-GspJ complex from the enterotoxigenic Escherichia coli type 2 secretion system
Konstantin V Korotkov1, Wim G J Hol
1Department of Biochemistry, Biomolecular Structure Center, University of Washington, Box 357742, Seattle, Washington 98195, USA.
Abstract:
Gram-negative bacteria translocate various proteins including virulence factors across their outer membrane via type 2 secretion systems (T2SSs). T2SSs are thought to contain a pseudopilus, a subcomplex formed by one major and several minor pseudopilins. We report the crystal structure of the complex formed by three minor pseudopilins from enterotoxigenic Escherichia coli. The GspK-GspI-GspJ complex has quasihelical characteristics and an architecture consistent with a localization at the pseudopilus tip. The alpha-domain of GspK has a previously unobserved fold with an unexpected dinuclear metal binding site. The area surrounding its disulfide bridge is conserved and might interact with other T2SS components or with secreted proteins.
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