2x1c

Publication Abstract from PubMed

Penicillium chrysogenum Acyl coenzyme A:isopenicillin N acyltransferase (AT) performs the last step in the biosynthesis of hydrophobic penicillins, exchanging the hydrophilic side chain of a precursor for various hydrophobic side chains. Like other N-terminal nucleophile hydrolases AT is produced as an inactive precursor that matures upon posttranslational cleavage. The structure of a Cys103Ala precursor mutant shows that maturation is autoproteolytic, initiated by Cys103 cleaving its preceding peptide bond. The crystal structure of the mature enzyme shows that after autoproteolysis residues 92-102 fold outwards, exposing a buried pocket. This pocket is structurally and chemically flexible and can accommodate substrates of different size and polarity. Modeling of a substrate-bound state indicates the residues important for catalysis. Comparison of the proposed autoproteolytic and substrate hydrolysis mechanisms shows that in both events the same catalytic residues are used, but that they perform different roles in catalysis.

Structures of an isopenicillin N converting Ntn-hydrolase reveal different catalytic roles for the active site residues of precursor and mature enzyme.,Bokhove M, Yoshida H, Hensgens CM, van der Laan JM, Sutherland JD, Dijkstra BW Structure. 2010 Mar 10;18(3):301-8. PMID:20223213^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.