2a78
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Crystal structure of the C3bot-RalA complex reveals a novel type of action of a bacterial exoenzyme
OverviewOverview
C3 exoenzymes from bacterial pathogens ADP-ribosylate and inactivate, low-molecular-mass GTPases of the Rho subfamily. Ral, a Ras subfamily, GTPase, binds the C3 exoenzymes from Clostridium botulinum and C. limosum, with high affinity without being a substrate for ADP ribosylation. In the, complex, the ADP-ribosyltransferase activity of C3 is blocked, while, binding of NAD and NAD-glycohydrolase activity remain. Here we report the, crystal structure of C3 from C. botulinum in a complex with GDP-bound RalA, at 1.8 A resolution. C3 binds RalA with a helix-loop-helix motif that is, adjacent to the active site. A quaternary complex with NAD suggests a mode, for ADP-ribosyltransferase inhibition. Interaction of C3 with RalA occurs, at a unique interface formed by the switch-II region, helix alpha3 and the, P loop of the GTPase. C3-binding stabilizes the GDP-bound conformation of, RalA and blocks nucleotide release. Our data indicate that C. botulinum, exoenzyme C3 is a single-domain toxin with bifunctional properties, targeting Rho GTPases by ADP ribosylation and Ral by a guanine nucleotide, dissociation inhibitor-like effect, which blocks nucleotide exchange.
About this StructureAbout this Structure
2A78 is a Protein complex structure of sequences from Clostridium botulinum d phage and Homo sapiens with MG and GDP as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the C3bot-RalA complex reveals a novel type of action of a bacterial exoenzyme., Pautsch A, Vogelsgesang M, Trankle J, Herrmann C, Aktories K, EMBO J. 2005 Oct 19;24(20):3670-80. Epub 2005 Sep 22. PMID:16177825
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