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Inosine Monophosphate Dehydrogenase (IMPDH) From Tritrichomonas Foetus with XMP and NAD boundInosine Monophosphate Dehydrogenase (IMPDH) From Tritrichomonas Foetus with XMP and NAD bound
Structural highlights
Function[IMDH_TRIFO] Catalyzes the conversion of inosine 5'-phosphate (IMP) to xanthosine 5'-phosphate (XMP), the first committed and rate-limiting step in the de novo synthesis of guanine nucleotides, and therefore plays an important role in the regulation of cell growth. Could also have a single-stranded nucleic acid-binding activity and could play a role in RNA and/or DNA metabolism.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe enzyme inosine monophosphate dehydrogenase (IMPDH) is responsible for the rate-limiting step in guanine nucleotide biosynthesis. Because it is up-regulated in rapidly proliferating cells, human type II IMPDH is actively targeted for immunosuppressive, anticancer, and antiviral chemotherapy. The enzyme employs a random-in ordered-out kinetic mechanism where substrate or cofactor can bind first but product is only released after the cofactor leaves. Due to structural and kinetic differences between mammalian and microbial enzymes, most drugs that are successful in the inhibition of mammalian IMPDH are far less effective against the microbial forms of the enzyme. It is possible that with greater knowledge of the structural mechanism of the microbial enzymes, an effective and selective inhibitor of microbial IMPDH will be developed for use as a drug against multi-drug resistant bacteria and protists. The high-resolution crystal structures of four different complexes of IMPDH from the protozoan parasite Tritrichomonas foetus have been solved: with its substrate IMP, IMP and the inhibitor mycophenolic acid (MPA), the product XMP with MPA, and XMP with the cofactor NAD(+). In addition, a potassium ion has been located at the dimer interface. A structural model for the kinetic mechanism is proposed. Crystal structures of Tritrichomonasfoetus inosine monophosphate dehydrogenase in complex with substrate, cofactor and analogs: a structural basis for the random-in ordered-out kinetic mechanism.,Prosise GL, Luecke H J Mol Biol. 2003 Feb 14;326(2):517-27. PMID:12559919[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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