PMID: 12684501

Authors:

Barends TR, Polderman-Tijmes JJ, Jekel PA, Hensgens CM, de Vries EJ, Janssen DB, Dijkstra BW

Title:

The sequence and crystal structure of the alpha-amino acid ester hydrolase from Xanthomonas citri define a new family of beta-lactam antibiotic acylases.

Journal:

J Biol Chem. 2003 Jun 20;278(25):23076-84. Epub 2003 Apr 8.

Abstract:

alpha-Amino acid ester hydrolases (AEHs) catalyze the hydrolysis and synthesis of esters and amides with an alpha-amino group. As such, they can synthesize beta-lactam antibiotics from acyl compounds and beta-lactam nuclei obtained from the hydrolysis of natural antibiotics. This article describes the gene sequence and the 1.9-A resolution crystal structure of the AEH from Xanthomonas citri. The enzyme consists of an alpha/beta-hydrolase fold domain, a helical cap domain, and a jellyroll beta-domain. Structural homology was observed to the Rhodococcus cocaine esterase, indicating that both enzymes belong to the same class of bacterial hydrolases. Docking of a beta-lactam antibiotic in the active site explains the substrate specificity, specifically the necessity of an alpha-amino group on the substrate, and explains the low specificity toward the beta-lactam nucleus.