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Applied and Environmental Microbiology, October 2006, p. 6554-6559, Vol. 72, No. 10
0099-2240/06/$08.00+0 doi:10.1128/AEM.00941-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
-Hydroxylase in Mycobacterium smegmatis mc2155
David A. Hopwood,2
Ferenc Jeanplong,1
Éva Ilk
y,1
Attila Kónya,1
István Kurucz,1 and
Gábor Ambrus1
Institute for Drug Research Ltd., 47-49 Berlini St., H-1045 Budapest, Hungary,1 John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom2
Received 20 April 2006/ Accepted 22 July 2006
Integration of the pCG79 temperature-sensitive plasmid carrying Tn611 was used to generate libraries of mutants with blocked sterol-transforming ability of the sterol-utilizing strains Mycobacterium smegmatis mc2155 and Mycobacterium phlei M51-Ept. Of the 10,000 insertional mutants screened from each library, 4 strains with altered activity of the sterol-degrading enzymes were identified. A blocked 4-androstene-3,17-dione-producing M. phlei mutant transformed sitosterol to 23,24-dinorcholane derivatives that are useful starting materials for corticosteroid syntheses. A recombinant plasmid, pFJ92, was constructed from the genomic DNA of one of the insertional mutants of M. smegmatis, 10A12, which was blocked in 3-ketosteroid 9
-hydroxylation and carrying the transposon insertion and flanking DNA sequences, and used to isolate a chromosomal fragment encoding the 9
-hydroxylase. The open reading frame encodes the 383-amino-acid terminal oxygenase of 3-ketosteroid 9
-hydroxylase in M. smegmatis mc2155 and has domains typically conserved in class IA terminal oxygenases. Escherichia coli containing the gene could hydroxylate the steroid ring at the 9
position.
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