1NVK

Crystal structures of the T4 phage beta-glucosyltransferase and the D100A mutant in complex with UDP-glucose: glucose binding and identification of the catalytic base for a direct displacement mechanism

(2003) J Mol Biol 330: 1077-1086

• PubMed: 12860129 Search on PubMed
• DOI: https://doi.org/10.1016/s0022-2836(03)00635-1
• Primary Citation of Related Structures:  
  1J39, 1NVK, 1NZD, 1NZF


• PubMed Abstract: 
  

  T4 phage beta-glucosyltransferase (BGT) is an inverting glycosyltransferase (GT) that transfers glucose from uridine diphospho-glucose (UDP-glucose) to an acceptor modified DNA. BGT belongs to the GT-B structural superfamily, represented, so far, by five different inverting or retaining GT families. Here, we report three high-resolution X-ray structures of BGT and a point mutant solved in the presence of UDP-glucose. The two co-crystal structures of the D100A mutant show that, unlike the wild-type enzyme, this mutation prevents glucose hydrolysis. This strongly indicates that Asp100 is the catalytic base. We obtained the wild-type BGT-UDP-glucose complex by soaking substrate-free BGT crystals. Comparison with a previous structure of BGT solved in the presence of the donor product UDP and an acceptor analogue provides the first model of an inverting GT-B enzyme in which both the donor and acceptor substrates are bound to the active site. The structural analyses support the in-line displacement reaction mechanism previously proposed, locate residues involved in donor substrate specificity and identify the catalytic base.

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Organizational Affiliation: 

Laboratoire d'Enzymologie et Biochimie Structurales UPR 9063 CNRS, Bât. 34, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.