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Double site saturation mutagenesis of the human cytochrome P450 2D6 results in regioselective steroid hydroxylation
Author(s) -
Geier Martina,
Braun Andreas,
Fladischer Patrik,
Stepniak Piotr,
Rudroff Florian,
Hametner Christian,
Mihovilovic Marko D.,
Glieder Anton
Publication year - 2013
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.12270
Subject(s) - hydroxylation , saturated mutagenesis , cytochrome p450 , regioselectivity , steroid , chemistry , active site , stereochemistry , enzyme , biochemistry , mutant , hormone , gene , catalysis
The human cytochrome P450 2D6 ( CYP 2D6) is one of the major human drug metabolizing enzymes and acts preferably on substrates containing a basic nitrogen atom. Testosterone − just as other steroids − is an atypical substrate and only poorly metabolized by CYP 2D6. The present study intended to investigate the influence of the two active site residues 216 and 483 on the capability of CYP 2D6 to hydroxylate steroids such as for example testosterone. All 400 possible combinatorial mutations at these two positions have been generated and expressed individually in P ichia pastoris . Employing whole‐cell biotransformations coupled with HPLC ‐ MS analysis the testosterone hydroxylase activity and regioselectivity of every single CYP 2D6 variant was determined. Covering the whole sequence space, CYP 2D6 variants with improved activity and so far unknown regio‐preference in testosterone hydroxylation were identified. Most intriguingly and in contrast to previous literature reports about mutein F483I, the mutation F483G led to preferred hydroxylation at the 2β‐position, while the slow formation of 6β‐hydroxytestosterone, the main product of wild‐type CYP 2D6, was further reduced. Two point mutations have already been sufficient to convert CYP 2D6 into a steroid hydroxylase with the highest ever reported testosterone hydroxylation rate for this enzyme, which is of the same order of magnitude as for the conversion of the standard substrate bufuralol by wild‐type CYP 2D6. Furthermore, this study is also an example for efficient human CYP engineering in P . pastoris for biocatalytic applications and to study so far unknown pharmacokinetic effects of individual and combined mutations in these key enzymes of the human drug metabolism.