Structural highlights
Function
[IMDH2_HUMAN] 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. It may also have a role in the development of malignancy and the growth progression of some tumors.[HAMAP-Rule:MF_03156]
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 PubMed
Inosine monophosphate dehydrogenase (IMPDH) controls a key metabolic step in the regulation of cell growth and differentiation. This step is the NAD-dependent oxidation of inosine 5' monophosphate (IMP) to xanthosine 5' monophosphate, the rate-limiting step in the synthesis of the guanine nucleotides. Two isoforms of IMPDH have been identified, one of which (type II) is significantly up- regulated in neoplastic and differentiating cells. As such, it has been identified as a major target in antitumor and immunosuppressive drug design. We present here the 2.9-A structure of a ternary complex of the human type II isoform of IMPDH. The complex contains the substrate analogue 6-chloropurine riboside 5'-monophosphate (6-Cl-IMP) and the NAD analogue selenazole-4-carboxamide adenine dinucleotide, the selenium derivative of the active metabolite of the antitumor drug tiazofurin. The enzyme forms a homotetramer, with the dinucleotide binding at the monomer-monomer interface. The 6 chloro-substituted purine base is dehalogenated, forming a covalent adduct at C6 with Cys-331. The dinucleotide selenazole base is stacked against the 6-Cl-IMP purine ring in an orientation consistent with the B-side stereochemistry of hydride transfer seen with NAD. The adenosine end of the ligand interacts with residues not conserved between the type I and type II isoforms, suggesting strategies for the design of isoform-specific agents.
Crystal structure of human type II inosine monophosphate dehydrogenase: implications for ligand binding and drug design.,Colby TD, Vanderveen K, Strickler MD, Markham GD, Goldstein BM Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3531-6. PMID:10097070[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Colby TD, Vanderveen K, Strickler MD, Markham GD, Goldstein BM. Crystal structure of human type II inosine monophosphate dehydrogenase: implications for ligand binding and drug design. Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3531-6. PMID:10097070
