Abstract

Deacetylcephalosporin C acetyltransferase (DAC-AT) catalyses the last step in the biosynthesis of cephalosporin C, a broad-spectrum beta-lactam antibiotic of large clinical importance. The acetyl transfer step has been suggested to be limiting for cephalosporin C biosynthesis, but has so far escaped detailed structural analysis. We present here the crystal structures of DAC-AT in complexes with reaction intermediates, providing crystallographic snapshots of the reaction mechanism. The enzyme is found to belong to the alpha/beta hydrolase class of acetyltransferases, and the structures support previous observations of a double displacement mechanism for the acetyl transfer reaction in other members of this class of enzymes. The structures of DAC-AT reported here provide evidence of a stable acyl - enzyme complex, thus underpinning a mechanism involving acetylation of a catalytic serine residue by acetyl coenzyme A, followed by transfer of the acetyl group to deacetylcephalosporin C through a suggested tetrahedral transition state. (c) 2008 Elsevier Ltd. All rights reserved.

Keywords

cephalosporin C; beta-lactam antibiotic biosynthesis; Acremonium chrysogenum; X-ray crystallography; acetyl transferase

Published in

Journal of Molecular Biology
2008, Volume: 377, number: 3, pages: 935-944

SLU Authors

• Valegård, Karin

  • Department of Molecular Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Biochemistry and Molecular Biology


Publication identifier

DOI: https://doi.org/10.1016/j.jmb.2008.01.047

Permanent link to this page (URI)

https://res.slu.se/id/publ/41029