2i5k
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(New page: 200px<br /><applet load="2i5k" size="450" color="white" frame="true" align="right" spinBox="true" caption="2i5k, resolution 3.100Å" /> '''Crystal structure o...)
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Revision as of 10:02, 21 November 2007
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Crystal structure of Ugp1p
Overview
UDP-glucose is the universal activated form of glucose, employed in all, organisms for glucosyl transfer reactions and as precursor for various, activated carbohydrates. In animal and fungal metabolism, UDP-glucose is, required for utilization of galactose and for the synthesis of glycogen, the major carbohydrate storage polymer. The formation of UDP-glucose is, catalyzed by UDP-glucose pyrophosphorylase (UGPase), which is highly, conserved among eukaryotes. Here, we present the crystal structure of, yeast UGPase, Ugp1p. Both in solution and in the crystal, Ugp1p forms, homooctamers, which represent the enzymatically active form of the, protein. Ugp1p subunits consist of three domains, with the active site, presumably located in the central SpsA GnT I core (SGC) domain. The, association in the octamer is mediated by contacts between left-handed, beta-helices in the C-terminal domains, forming a toroidal solenoid, structure in the core of the complex. The catalytic domains attached to, this scaffold core do not directly contact each other, consistent with, simple Michaelis-Menten kinetics found for Ugp1p. Conservation of, hydrophobic residues at the subunit interfaces suggests that all fungal, and animal homologs form this quarternary structure arrangement in, contrast to monomeric plant UGPases, which have charged residues at these, positions. Implications of this oligomeric arrangement for regulation of, UGPase activity in fungi and animals are discussed.
About this Structure
2I5K is a Single protein structure of sequence from Saccharomyces cerevisiae. Active as UTP--glucose-1-phosphate uridylyltransferase, with EC number 2.7.7.9 Full crystallographic information is available from OCA.
Reference
Structural basis for subunit assembly in UDP-glucose pyrophosphorylase from Saccharomyces cerevisiae., Roeben A, Plitzko JM, Korner R, Bottcher UM, Siegers K, Hayer-Hartl M, Bracher A, J Mol Biol. 2006 Dec 8;364(4):551-60. Epub 2006 Sep 1. PMID:17010990
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