2bz0

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spinqualitylabelsall models 2bz0, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF E. COLI GTP CYCLOHYDROLASE II IN COMPLEX WITH GTP ANALOGUE, GMPCPP, AND ZINC

Overview

GTP cyclohydrolase II converts GTP to 2,5-diamino-6-beta-ribosyl-4(3H)-pyrimidinone 5'-phosphate, formate and pyrophosphate, the first step in riboflavin biosynthesis. The essential role of riboflavin in metabolism and the absence of GTP cyclohydrolase II in higher eukaryotes makes it a potential novel selective antimicrobial drug target. GTP cyclohydrolase II catalyzes a distinctive overall reaction from GTP cyclohydrolase I; the latter converts GTP to dihydroneopterin triphosphate, utilized in folate and tetrahydrobiopterin biosynthesis. The structure of GTP cyclohydrolase II determined at 1.54-A resolution reveals both a different protein fold to GTP cyclohydrolase I and distinctive molecular recognition determinants for GTP; although in both enzymes there is a bound catalytic zinc. The GTP cyclohydrolase II.GMPCPP complex structure shows Arg(128) interacting with the alpha-phosphonate, and thus in the case of GTP, Arg(128) is positioned to act as the nucleophile for pyrophosphate release and formation of the proposed covalent guanylyl-GTP cyclohydrolase II intermediate. Tyr(105) is identified as playing a key role in GTP ring opening; it is hydrogen-bonded to the zinc-activated water molecule, the latter being positioned for nucleophilic attack on the guanine C-8 atom. Although GTP cyclohydrolase I and GTP cyclohydrolase II both use a zinc ion for the GTP ring opening and formate release, different residues are utilized in each case to catalyze this reaction step.

About this Structure

2BZ0 is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as GTP cyclohydrolase II, with EC number 3.5.4.25 Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

GTP cyclohydrolase II structure and mechanism., Ren J, Kotaka M, Lockyer M, Lamb HK, Hawkins AR, Stammers DK, J Biol Chem. 2005 Nov 4;280(44):36912-9. Epub 2005 Aug 22. PMID:16115872

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