1b5e
DCMP HYDROXYMETHYLASE FROM T4
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OverviewOverview
Bacteriophage T4 deoxycytidylate hydroxymethylase (EC 2.1.2.8), a, homodimer of 246-residue subunits, catalyzes hydroxymethylation of the, cytosine base in deoxycytidylate (dCMP) to produce 5-hydroxymethyl-dCMP., It forms part of a phage DNA protection system and appears to function in, vivo as a component of a multienzyme complex called deoxyribonucleoside, triphosphate (dNTP) synthetase. We have determined its crystal structure, in the presence of the substrate dCMP at 1.6 A resolution. The structure, reveals a subunit fold and a dimerization pattern in common with, thymidylate synthases, despite low (approximately 20%) sequence identity., Among the residues that form the dCMP binding site, those interacting with, the sugar and phosphate are arranged in a configuration similar to the, deoxyuridylate binding site of thymidylate synthases. However, the, residues interacting directly or indirectly with the cytosine base show a, more divergent structure and the presumed folate cofactor binding site is, more open. Our structure reveals a water molecule properly positioned near, C-6 of cytosine to add to the C-7 methylene intermediate during the last, step of hydroxymethylation. On the basis of sequence comparison and, crystal packing analysis, a hypothetical model for the interaction between, T4 deoxycytidylate hydroxymethylase and T4 thymidylate synthase in the, dNTP-synthesizing complex has been built.
About this StructureAbout this Structure
1B5E is a Single protein structure of sequence from Enterobacteria phage t2 with as ligand. Active as Deoxycytidylate 5-hydroxymethyltransferase, with EC number 2.1.2.8 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of deoxycytidylate hydroxymethylase from bacteriophage T4, a component of the deoxyribonucleoside triphosphate-synthesizing complex., Song HK, Sohn SH, Suh SW, EMBO J. 1999 Mar 1;18(5):1104-13. PMID:10064578
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