1cg6
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STRUCTURE OF HUMAN 5'-DEOXY-5'-METHYLTHIOADENOSINE PHOSPHORYLASE COMPLEXED WITH 5'-DEOXY-5'-METHYLTHIOADENOSINE AND SULFATE AT 1.7 A RESOLUTION
OverviewOverview
BACKGROUND: 5'-Deoxy-5'-methylthioadenosine phosphorylase (MTAP) catalyzes, the reversible phosphorolysis of 5'-deoxy-5'-methylthioadenosine (MTA) to, adenine and 5-methylthio-D-ribose-1-phosphate. MTA is a by-product of, polyamine biosynthesis, which is essential for cell growth and, proliferation. This salvage reaction is the principle source of free, adenine in human cells. Because of its importance in coupling the purine, salvage pathway to polyamine biosynthesis MTAP is a potential, chemotherapeutic target. RESULTS: We have determined the crystal structure, of MTAP at 1.7 A resolution using multiwavelength anomalous diffraction, phasing techniques. MTAP is a trimer comprised of three identical, subunits. Each subunit consists of a single alpha/beta domain containing a, central eight-stranded mixed beta sheet, a smaller five-stranded mixed, beta sheet and six alpha helices. The native structure revealed the, presence of an adenine molecule in the purine-binding site. The structure, of MTAP with methylthioadenosine and sulfate ion soaked into the active, site was also determined using diffraction data to 1.7 A resolution., CONCLUSIONS: The overall quaternary structure and subunit topology of MTAP, are similar to mammalian purine nucleoside phosphorylase (PNP). The, structures of the MTAP-ligand complexes provide a map of the active site, and suggest possible roles for specific residues in substrate binding and, catalysis. Residues accounting for the differences in substrate, specificity between MTAP and PNP are also identified. Detailed information, about the structure and chemical nature of the MTAP active site will aid, in the rational design of inhibitors of this potential chemotherapeutic, target. The MTAP structure represents the first structure of a mammalian, PNP that is specific for 6-aminopurines.
About this StructureAbout this Structure
1CG6 is a Single protein structure of sequence from Homo sapiens with SO4 and MTA as ligands. Active as S-methyl-5-thioadenosine phosphorylase, with EC number 2.4.2.28 Full crystallographic information is available from OCA.
ReferenceReference
The structure of human 5'-deoxy-5'-methylthioadenosine phosphorylase at 1.7 A resolution provides insights into substrate binding and catalysis., Appleby TC, Erion MD, Ealick SE, Structure. 1999 Jun 15;7(6):629-41. PMID:10404592
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