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Regioselective Acetylation of C21 Hydroxysteroids by the Bacterial Chloramphenicol Acetyltransferase I
Author(s) -
Mosa Azzam,
Hutter Michael C.,
Zapp Josef,
Bernhardt Rita,
Hannemann Frank
Publication year - 2015
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201500125
Subject(s) - chloramphenicol acetyltransferase , acetyltransferase , acetylation , escherichia coli , regioselectivity , biotransformation , chemistry , chloramphenicol , biocatalysis , biochemistry , reporter gene , enzyme , stereochemistry , combinatorial chemistry , gene , gene expression , antibiotics , catalysis , ionic liquid
Abstract Chloramphenicol acetyltransferase I (CATI) detoxifies the antibiotic chloramphenicol and confers a corresponding resistance to bacteria. In this study we identified this enzyme as a steroid acetyltransferase and designed a new and efficient Escherichia‐coli ‐based biocatalyst for the regioselective acetylation of C21 hydroxy groups in steroids of pharmaceutical interest. The cells carried a recombinant catI gene controlled by a constitutive promoter. The capacity of the whole‐cell system to modify different hydroxysteroids was investigated, and NMR spectroscopy revealed that all substrates were selectively transformed into the corresponding 21‐acetoxy derivatives. The biotransformation was optimized, and the reaction mechanism is discussed on the basis of a computationally modeled substrate docking into the crystal structure of CATI.