1h5r
From Proteopedia
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THYMIDYLYLTRANSFERASE COMPLEXED WITH THIMIDINE AND GLUCOSE-1-PHOSPATE
Overview
Glucose-1-phosphate thymidylyltransferase is the first enzyme in the, biosynthesis of dTDP-l-rhamnose, the precursor of l-rhamnose, an essential, component of surface antigens, such as the O-lipopolysaccharide, mediating, virulence and adhesion to host tissues in many microorganisms. The enzyme, catalyses the formation of dTDP-glucose, from dTTP and glucose, 1-phosphate, as well as its pyrophosphorolysis. To shed more light on the, catalytic properties of glucose-1-phosphate thymidylyltransferase from, Escherichia coli, specifically distinguishing between ping pong and, sequential ordered bi bi reaction mechanisms, the enzyme kinetic, properties have been analysed in the presence of different substrates and, inhibitors. Moreover, three different complexes of glucose-1-phosphate, thymidylyltransferase (co-crystallized with dTDP, with dTMP and, glucose-1-phosphate, with d-thymidine and glucose-1-phosphate) have been, analysed by X-ray crystallography, in the 1.9-2.3 A resolution range, (R-factors of 17.3-17.5 %). The homotetrameric enzyme shows strongly, conserved substrate/inhibitor binding modes in a surface cavity next to, the topological switch-point of a quasi-Rossmann fold. Inspection of the, subunit tertiary structure reveals relationships to other enzymes involved, in the biosynthesis of nucleotide-sugars, including distant proteins such, as the molybdenum cofactor biosynthesis protein MobA. The precise location, of the substrate relative to putative reactive residues in the catalytic, center suggests that, in keeping with the results of the kinetic, measurements, both catalysed reactions, i.e. dTDP-glucose biosynthesis and, pyrophosphorolysis, follow a sequential ordered bi bi catalytic mechanism.
About this Structure
1H5R is a Protein complex structure of sequences from [1] with G1P, SO4 and THM as ligands. Active as Glucose-1-phosphate thymidylyltransferase, with EC number 2.7.7.24 Structure known Active Site: THM. Full crystallographic information is available from OCA.
Reference
Kinetic and crystallographic analyses support a sequential-ordered bi bi catalytic mechanism for Escherichia coli glucose-1-phosphate thymidylyltransferase., Zuccotti S, Zanardi D, Rosano C, Sturla L, Tonetti M, Bolognesi M, J Mol Biol. 2001 Nov 2;313(4):831-43. PMID:11697907
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