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1lrt

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{{STRUCTURE_1lrt| PDB=1lrt | SCENE= }}
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'''CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME'''
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===CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME===
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==Overview==
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Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the conversion of IMP to XMP with the reduction of NAD(+), which is the rate-limiting step in the biosynthesis of guanine nucleotides. IMPDH is a promising target for chemotherapy. Microbial IMPDHs differ from mammalian enzymes in their lower affinity for inhibitors such as mycophenolic acid (MPA) and thiazole-4-carboxamide adenine dinucleotide (TAD). Part of this resistance is determined by the coupling between nicotinamide and adenosine subsites in the NAD(+) binding site that is postulated to involve an active site flap. To understand the structural basis of the drug selectivity, we solved the X-ray crystal structure of the catalytic core domain of Tritrichomonas foetus IMPDH in complex with IMP and beta-methylene-TAD at 2.2 A resolution. Unlike previous structures of this enzyme, the active site loop is ordered in this complex, and the catalytic Cys319 is 3.6 A from IMP, in the same plane as the hypoxanthine ring. The active site loop forms hydrogen bonds to the carboxamide of beta-Me-TAD which suggests that NAD(+) promotes the nucleophillic attack of Cys319 on IMP. The interactions of the adenosine end of TAD are very different from those in the human enzyme, suggesting the NAD(+) site may be an exploitable target for the design of antimicrobial drugs. In addition, a new K(+) site is observed at the subunit interface. This site is adjacent to beta-Me-TAD, consistent with the link between the K(+) activation and NAD(+). However, contrary to the coupling model, the flap does not cover the adenosine subsite and remains largely disordered.
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{{ABSTRACT_PUBMED_12403633}}
==About this Structure==
==About this Structure==
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[[Category: Flexible loop]]
[[Category: Flexible loop]]
[[Category: Ternary complex]]
[[Category: Ternary complex]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 00:13:24 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 21:54:40 2008''

Revision as of 18:54, 2 July 2008

Image:1lrt.png

Template:STRUCTURE 1lrt

CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME

Template:ABSTRACT PUBMED 12403633

About this Structure

1LRT is a Single protein structure of sequence from Tritrichomonas foetus. Full crystallographic information is available from OCA.

Reference

Crystal structure of a ternary complex of Tritrichomonas foetus inosine 5'-monophosphate dehydrogenase: NAD+ orients the active site loop for catalysis., Gan L, Petsko GA, Hedstrom L, Biochemistry. 2002 Nov 5;41(44):13309-17. PMID:12403633

Page seeded by OCA on Wed Jul 2 21:54:40 2008

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