11β‐Hydroxylase Activity in Recombinant Yeast Mitochondria In vivo Conversion of 11‐Deoxycortisol to Hydrocortisone

• Published in: European journal of biochemistry Vol. 238; no. 2; pp. 495 - 504
• Main Authors: Dumas, Bruno, Cauet, Gilles, Lacour, Thierry, Degryse, Eric, Laruelle, Laurence, Ledoux, Catherine, Spagnoli, Roberto, Achstetter, Tilman
• Format: Journal Article
• Language: English
• Published: 01-06-1996
• ISSN: 0014-2956; 1432-1033
• DOI: 10.1111/j.1432-1033.1996.0495z.x

In mammals, the final 11β‐hydroxylation step of the hydrocortisone biosynthesis pathway is performed by a mitochondrial enzyme, namely cytochrome
P
‐450
11β
, together with the electron carriers adrenodoxin and NADPH adrenodoxin oxidoreductase. Successful production of a functional steroid 11β‐hydroxylase activity was obtained in recombinant yeast
in vivo.
This conversion was achieved by coexpression of a mitochondrially targeted adrenodoxin and a modified bovine
P
‐450
11β
whose natural presequence was replaced by a yeast presequence, together with an unexpected yeast endogenous NADPH‐adrenodoxin‐reductase‐like activity. Adrenodoxin and
P
‐450
11β
behave as a mitochondrial matrix and membrane protein, respectively.
Saccharomyces cerevisiae
apparently produces a mitochondrial protein which is capable of transferring electrons to bovine adrenodoxin, which in turn transfers the electrons to
P
‐450
11β
. The endogenous adrenodoxin oxidoreductase gains electrons specifically from NADPH.
The notion that a yeast microsomal NADPH
P
‐450 oxidoreductase can transfer electrons to mammalian microsomal
P
‐450s can be extended to mitochondria, where an NADPH adrenodoxin oxidoreductase protein transfers electrons to adrenodoxin and renders a mitochondrial mammalian
P
‐450 functional
in vivo.
The physiological function of this yeast NADPH adrenodoxin oxidoreductase activity is not known.