The Donor Subsite of Trehalose-6-Phosphate Synthase: Binary Complexes with Udp-Glucose and Udp-2-Deoxy-2-Fluoro-Glucose at 2 A ResolutionGibson, R.P., Tarling, C.A., Roberts, S., Withers, S.G., Davies, G.J.
(2004) J.Biol.Chem. 279: 1950
- PubMed: 14570926
- DOI: 10.1074/jbc.M307643200
- Primary Citation of Related Structures:  1UQU
- PubMed Abstract:
- Insights Into Trehalose Synthesis Provided by the Structure of the Retaining Glycosyltransferase Otsa
Gibson, R.P.,Turkenburg, J.P.,Charnock, S.J.,Lloyd, R.,Davies, G.J.
(2002) Chem.Biol. 9: 1337
Trehalose is an unusual non-reducing disaccharide that plays a variety of biological roles, from food storage to cellular protection from environmental stresses such as desiccation, pressure, heat-shock, extreme cold, and oxygen radicals. It is also ...
Trehalose is an unusual non-reducing disaccharide that plays a variety of biological roles, from food storage to cellular protection from environmental stresses such as desiccation, pressure, heat-shock, extreme cold, and oxygen radicals. It is also an integral component of the cell-wall glycolipids of mycobacteria. The primary enzymatic route to trehalose first involves the transfer of glucose from a UDP-glucose donor to glucose-6-phosphate to form alpha,alpha-1,1 trehalose-6-phosphate. This reaction, in which the configurations of two glycosidic bonds are set simultaneously, is catalyzed by the glycosyltransferase trehalose-6-phosphate synthase (OtsA), which acts with retention of the anomeric configuration of the UDP-sugar donor. The classification of activated sugar-dependent glycosyltransferases into approximately 70 distinct families based upon amino acid sequence similarities places OtsA in glycosyltransferase family 20 (see afmb.cnrs-mrs.fr/CAZY/). The recent 2.4 A structure of Escherichia coli OtsA revealed a two-domain enzyme with catalysis occurring at the interface of the twin beta/alpha/beta domains. Here we present the 2.0 A structures of the E. coli OtsA in complex with either UDP-Glc or the non-transferable analogue UDP-2-deoxy-2-fluoroglucose. Both complexes unveil the donor subsite interactions, confirming a strong similarity to glycogen phosphorylases, and reveal substantial conformational differences to the previously reported complex with UDP and glucose 6-phosphate. Both the relative orientation of the two domains and substantial (up to 10 A) movements of an N-terminal loop (residues 9-22) characterize the more open "relaxed" conformation of the binary UDP-sugar complexes reported here.
Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, United Kingdom.