Molecular analysis of the Vibrio cholerae type II secretion ATPase EpsE.

TitleMolecular analysis of the Vibrio cholerae type II secretion ATPase EpsE.
Publication TypeJournal Article
Year of Publication2005
AuthorsCamberg, JL, Sandkvist, M
JournalJ Bacteriol
Volume187
Issue1
Pagination249-56
Date Published2005 Jan
ISSN0021-9193
KeywordsAdenosine Triphosphate, Bacterial Proteins, Membrane Proteins, Vibrio cholerae, Zinc
Abstract

<p>The type II secretion system is a macromolecular assembly that facilitates the extracellular translocation of folded proteins in gram-negative bacteria. EpsE, a member of this secretion system in Vibrio cholerae, contains a nucleotide-binding motif composed of Walker A and B boxes that are thought to participate in binding and hydrolysis of ATP and displays structural homology to other transport ATPases. Here we demonstrate that purified EpsE is an Mg2+-dependent ATPase and define optimal conditions for the hydrolysis reaction. EpsE displays concentration-dependent activity, which may suggest that the active form is oligomeric. Size exclusion chromatography showed that the majority of purified EpsE is monomeric; however, detailed analyses of specific activities obtained following gel filtration revealed the presence of a small population of active oligomers. We further report that EpsE binds zinc through a tetracysteine motif near its carboxyl terminus, yet metal displacement assays suggest that zinc is not required for catalysis. Previous studies describing interactions between EpsE and other components of the type II secretion pathway together with these data further support the hypothesis that EpsE functions to couple energy to the type II apparatus, thus enabling secretion.</p>

DOI10.1128/JB.187.1.249-256.2005
Alternate JournalJ. Bacteriol.
PubMed ID15601709
PubMed Central IDPMC538811
Grant ListT32 HL007698 / HL / NHLBI NIH HHS / United States
R56 AI049294 / AI / NIAID NIH HHS / United States
AI49294 / AI / NIAID NIH HHS / United States
R01 AI049294 / AI / NIAID NIH HHS / United States
HL007698 / HL / NHLBI NIH HHS / United States