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2gq2
From Proteopedia
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Mycobacterium tuberculosis ThyX-NADP complex
Overview
The novel flavin-dependent thymidylate synthase, ThyX, is absent in humans but several pathogenic bacteria depend exclusively on ThyX activity to synthesize thymidylate. Reduction of the enzyme-bound FAD by NADPH is suggested to be the critical first step in ThyX catalysis. We soaked Mycobacterium tuberculosis ThyX-FAD-BrdUMP ternary complex crystals in a solution containing NADP+ to gain structural insights into the reductive step of the catalytic cycle. Surprisingly, the NADP+ displaced both FAD and BrdUMP from the active site. In the resultant ThyX-NADP+ binary complex, the AMP moiety is bound in a deep pocket similar to that of the same moiety of FAD in the ternary complex, while the nicotinamide part of NADP+ is engaged in a limited number of contacts with ThyX. The additional 2'-phosphate group attached to the AMP ribose of NADP+ could be accommodated with minor rearrangement of water molecules. The newly introduced 2'-phosphate groups are engaged in water-mediated interactions across the non-crystallographic 2-fold axis of the ThyX tetramer, suggesting possibilities for design of high-affinity bivalent inhibitors of this intriguing enzyme.
About this Structure
2GQ2 is a Single protein structure of sequence from Mycobacterium tuberculosis with , , , and as ligands. Active as Thymidylate synthase (FAD), with EC number 2.1.1.148 Full crystallographic information is available from OCA.
Reference
NADP+ expels both the co-factor and a substrate analog from the Mycobacterium tuberculosis ThyX active site: opportunities for anti-bacterial drug design., Sampathkumar P, Turley S, Sibley CH, Hol WG, J Mol Biol. 2006 Jun 30;360(1):1-6. Epub 2006 May 12. PMID:16730023
Page seeded by OCA on Thu Feb 21 17:34:07 2008
