NADP+ expels both the co-factor and a substrate analog from the Mycobacterium tuberculosis ThyX active site: opportunities for anti-bacterial drug design.
J Mol Biol
; 360(1): 1-6, 2006 Jun 30.
Article
em En
| MEDLINE
| ID: mdl-16730023
ABSTRACT
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.
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Base de dados:
MEDLINE
Assunto principal:
Anti-Infecciosos
/
Mycobacterium tuberculosis
/
NADP
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2006
Tipo de documento:
Article