1gzf

From Proteopedia

Revision as of 07:44, 3 February 2008

STRUCTURE OF THE CLOSTRIDIUM BOTULINUM C3 EXOENZYME (WILD-TYPE) IN COMPLEX WITH NAD

Overview

We have solved the crystal structures of Clostridium botulinum C3, exoenzyme free and complexed to NAD in the same crystal form, at 2.7 and, 1.95 A, respectively. The asymmetric unit contains four molecules, which, in the free form, share the same conformation. Upon NAD binding, C3, underwent various conformational changes, whose amplitudes were, differentially limited in the four molecules of the crystal unit. A major, rearrangement concerns the loop that contains the functionally important, ARTT motif (ADP-ribosyltransferase toxin turn-turn). The ARTT loop, undergoes an ample swinging motion to adopt a conformation that covers the, nicotinamide moiety of NAD. In particular, Gln-212, which belongs to the, ARTT motif, flips over from a solvent-exposed environment to a buried, conformation in the NAD binding pocket. Mutational experiments showed that, Gln-212 is neither involved in NAD binding nor in the NAD-glycohydrolase, activity of C3, whereas it plays a critical role in the ADP-ribosyl, transfer to the substrate Rho. We observed additional NAD-induced, movements, including a crab-claw motion of a subdomain that closes the NAD, binding pocket. The data emphasized a remarkable NAD-induced plasticity of, the C3 binding pocket and suggest that the NAD-induced ARTT loop, conformation may be favored by the C3-NAD complex to bind to the substrate, Rho. Our structural observations, together with a number of mutational, experiments suggest that the mechanisms of Rho ADP-ribosylation by C3-NAD, may be more complex than initially anticipated.

About this Structure

1GZF is a Single protein structure of sequence from Clostridium botulinum with , , and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

NAD binding induces conformational changes in Rho ADP-ribosylating clostridium botulinum C3 exoenzyme., Menetrey J, Flatau G, Stura EA, Charbonnier JB, Gas F, Teulon JM, Le Du MH, Boquet P, Menez A, J Biol Chem. 2002 Aug 23;277(34):30950-7. Epub 2002 May 23. PMID:12029083

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