TY - JOUR
T1 - Characterization and catalytic properties of the sterol 14α-demethylase from Mycobacterium tuberculosis
AU - Bellamine, Aouatef
AU - Mangla, Anil T.
AU - Nes, W. David
AU - Waterman, Michael R.
PY - 1999/8/3
Y1 - 1999/8/3
N2 - Sterol 14α-demethylase encoded by CYP51 is a mixed-function oxidase involved in sterol synthesis in eukaryotic organisms. Completion of the Mycobacterium tuberculosis genome project revealed that a protein having homology to mammalian 14α-demethylases might be present in this bacterium. Using genomic DNA from mycobacterial strain H37Rv, we have established unambiguously that the CYP51-like gene encodes a bacterial sterol 14α- demethylase. Expression of the M. tuberculosis CYP51 gene in Escherichia coli yields a P450, which, when purified to homogeneity, has the predicted molecular mass, ca. 50 kDa on SDS/PAGE, and binds both sterol substrates and azole inhibitors of P450 14α-demethylases. It catalyzes 14α-demethylation of lanosterol, 24,25-dihydrolanosterol, and obtusifoliol to produce the 8,14- dienes stereoselectively as shown by GC/MS and 1H NMR analysis. Both flavodoxin and ferredoxin redox systems are able to support this enzymatic activity. Structural requirements of a 14α-methyl group and Δ(8(9))-bond were established by comparing binding of pairs of sterol substrate that differed in a single molecular feature, e.g., cycloartenol paired with lanosterol. These substrate requirements are similar to those established for plant and animal P450 14α-demethylases. From the combination of results, the interrelationships of substrate functional groups within the active site show that oxidative portions of the sterol biosynthetic pathway are present in prokaryotes.
AB - Sterol 14α-demethylase encoded by CYP51 is a mixed-function oxidase involved in sterol synthesis in eukaryotic organisms. Completion of the Mycobacterium tuberculosis genome project revealed that a protein having homology to mammalian 14α-demethylases might be present in this bacterium. Using genomic DNA from mycobacterial strain H37Rv, we have established unambiguously that the CYP51-like gene encodes a bacterial sterol 14α- demethylase. Expression of the M. tuberculosis CYP51 gene in Escherichia coli yields a P450, which, when purified to homogeneity, has the predicted molecular mass, ca. 50 kDa on SDS/PAGE, and binds both sterol substrates and azole inhibitors of P450 14α-demethylases. It catalyzes 14α-demethylation of lanosterol, 24,25-dihydrolanosterol, and obtusifoliol to produce the 8,14- dienes stereoselectively as shown by GC/MS and 1H NMR analysis. Both flavodoxin and ferredoxin redox systems are able to support this enzymatic activity. Structural requirements of a 14α-methyl group and Δ(8(9))-bond were established by comparing binding of pairs of sterol substrate that differed in a single molecular feature, e.g., cycloartenol paired with lanosterol. These substrate requirements are similar to those established for plant and animal P450 14α-demethylases. From the combination of results, the interrelationships of substrate functional groups within the active site show that oxidative portions of the sterol biosynthetic pathway are present in prokaryotes.
UR - http://www.scopus.com/inward/record.url?scp=0033529797&partnerID=8YFLogxK
U2 - 10.1073/pnas.96.16.8937
DO - 10.1073/pnas.96.16.8937
M3 - Article
C2 - 10430874
AN - SCOPUS:0033529797
SN - 0027-8424
VL - 96
SP - 8937
EP - 8942
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 16
ER -