1lrt
From Proteopedia
(New page: 200px<br /><applet load="1lrt" size="450" color="white" frame="true" align="right" spinBox="true" caption="1lrt, resolution 2.20Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1lrt.jpg|left|200px]]<br /><applet load="1lrt" size=" | + | [[Image:1lrt.jpg|left|200px]]<br /><applet load="1lrt" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1lrt, resolution 2.20Å" /> | caption="1lrt, resolution 2.20Å" /> | ||
'''CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME'''<br /> | '''CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the conversion of | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1LRT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Tritrichomonas_foetus Tritrichomonas foetus] with BOG, K, IMP, TAD and TRS as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/IMP_dehydrogenase IMP dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.205 1.1.1.205] Full crystallographic information is available from [http:// | + | 1LRT is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Tritrichomonas_foetus Tritrichomonas foetus] with <scene name='pdbligand=BOG:'>BOG</scene>, <scene name='pdbligand=K:'>K</scene>, <scene name='pdbligand=IMP:'>IMP</scene>, <scene name='pdbligand=TAD:'>TAD</scene> and <scene name='pdbligand=TRS:'>TRS</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/IMP_dehydrogenase IMP dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.205 1.1.1.205] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LRT OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Gan, L.]] | [[Category: Gan, L.]] | ||
[[Category: Hedstrom, L.]] | [[Category: Hedstrom, L.]] | ||
| - | [[Category: Petsko, G | + | [[Category: Petsko, G A.]] |
[[Category: BOG]] | [[Category: BOG]] | ||
[[Category: IMP]] | [[Category: IMP]] | ||
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[[Category: ternary complex]] | [[Category: ternary complex]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:47:47 2008'' |
Revision as of 11:47, 21 February 2008
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CRYSTAL STRUCTURE OF TERNARY COMPLEX OF TRITRICHOMONAS FOETUS INOSINE-5'-MONOPHOSPHATE DEHYDROGENASE: STRUCTURAL CHARACTERIZATION OF NAD+ SITE IN MICROBIAL ENZYME
Overview
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.
About this Structure
1LRT is a Single protein structure of sequence from Tritrichomonas foetus with , , , and as ligands. Active as IMP dehydrogenase, with EC number 1.1.1.205 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 Thu Feb 21 13:47:47 2008
Categories: IMP dehydrogenase | Single protein | Tritrichomonas foetus | Gan, L. | Hedstrom, L. | Petsko, G A. | BOG | IMP | K | TAD | TRS | Alpha-beta barrel | Flap | Flexible loop | Ternary complex
