2p56

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spinqualitylabelsall models 2p56, resolution 2.200Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of alpha-2,3-sialyltransferase from Campylobacter jejuni in apo form

Overview

Sialic acid is an essential sugar in biology that plays key roles in, numerous cellular processes and interactions. The biosynthesis of, sialylated glycoconjugates is catalyzed by five distinct families of, sialyltransferases. In the last 25 years, there has been much research on, the enzymes themselves, their genes, and their reaction products, but we, still do not know the precise molecular mechanism of action for this class, of glycosyltransferase. We previously reported the first detailed, structural and kinetic characterization of Cst-II, a bifunctional, sialyltransferase (CAZy GT-42) from the bacterium Campylobacter jejuni, [Chiu et al. (2004) Nat. Struct. Mol. Biol. 11, 163-170]. This enzyme can, use both Gal-beta-1,3/4-R and Neu5Ac-alpha-2,3-Gal-beta-1,3/4-R as, acceptor sugars. A second sialyltransferase from this bacterium, Cst-I, has been shown to utilize solely Gal-beta-1,3/4-R as the acceptor sugar in, its transferase reaction. We report here the structural and kinetic, characterization of this monofunctional enzyme, which belongs to the same, sialyltransferase family as Cst-II, in both apo and substrate bound form., Our structural data show that Cst-I adopts a similar GTA-type, glycosyltransferase fold to that of the bifunctional Cst-II, with, conservation of several key noncharged catalytic residues. Significant, differences are found, however, between the two enzymes in the lid domain, region, which is critical to the creation of the acceptor sugar binding, site. Furthermore, molecular modeling of various acceptor sugars within, the active sites of these enzymes provides significant new insights into, the structural basis for substrate specificities within this biologically, important enzyme class.

About this Structure

2P56 is a Single protein structure of sequence from Campylobacter jejuni with as ligand. Full crystallographic information is available from OCA.

Reference

Structural analysis of the alpha-2,3-sialyltransferase Cst-I from Campylobacter jejuni in Apo and substrate-analogue bound forms., Chiu CP, Lairson LL, Gilbert M, Wakarchuk WW, Withers SG, Strynadka NC, Biochemistry. 2007 Jun 19;46(24):7196-204. Epub 2007 May 23. PMID:17518445

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