Michael Waterman
Faculty Member
Last active: 2/12/2015

Substrate recognition sites in 14alpha-sterol demethylase from comparative analysis of amino acid sequences and X-ray structure of Mycobacterium tuberculosis CYP51.

Podust LM, Stojan J, Poulos TL, Waterman MR
J Inorg Biochem. 2001 87 (4): 227-35

PMID: 11744060 · DOI:10.1016/s0162-0134(01)00388-9

The crystal structure of 14alpha-sterol demethylase from Mycobacterium tuberculosis (MTCYP51) [Proc. Natl. Acad. Sci. USA 98 (2001) 3068-3073] provides a template for analysis of eukaryotic orthologs which constitute the CYP51 family of cytochrome P450 proteins. Putative substrate recognition sites (SRSs) were identified in MTCYP51 based on the X-ray structures and have been compared with SRSs predicted based on Gotoh's analysis [J. Biol. Chem. 267 (1992) 83-90]. While Gotoh's SRS-4, 5, and 6 contribute in formation of the putative MTCYP51 substrate binding site, SRS-2 and 3 likely do not exist in MTCYP51. SRS-1, as part of the open BC loop, in the conformation found in the crystal can provide only limited contacts with the sterol. However, its role in substrate binding might dramatically increase if the loop closes in response to substrate binding. Thus, while the notion of SRSs has been very useful in leading to our current understanding of P450 structure and function, their identification by sequence alignment between distant P450 families will not necessarily be a good predictor of residues associated with substrate binding. Localization of CYP51 mutation hotspots in Candida albicans azole resistant isolates was analyzed with respect to SRSs. These mutations are found to be outside of the putative substrate interacting sites indicating the preservation of the protein active site under the pressure of azole treatment. Since the mutations residing outside the putative CYP51 active side can profoundly influence ligand binding within the active site, perhaps they provide insight into the basis of evolutionary changes which have occurred leading to different P450s.

MeSH Terms (12)

Amino Acid Sequence Binding Sites Crystallography, X-Ray Cytochrome P-450 Enzyme System Lanosterol Models, Molecular Molecular Sequence Data Mycobacterium tuberculosis Oxidoreductases Sequence Alignment Sterol 14-Demethylase Substrate Specificity

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