Expression and homology modelling of sterol 14a-demethylase of Magnaporthe grisea and its interaction with azoles

BACKGROUND: Magnaporthe grisea (Hebert) ME Barr infection is one of the most serious diseases for cultivated rice in the world. Sterol 14-demethylase (CYP51) is an important drug target for microbial pathogenic infections. To exploit specific and effective fungicides for M. grisea better, the authors have analysed the characteristics of interaction between sterol 14-demethylase from M. grisea (MGCYP51) and azoles. MGCYP51 with truncation of N-terminal residues was cloned and expressed in E. coli, difference binding spectra of MGCYP51 induced by addition of four commercial azoles were determined and molecular modelling of MGCYP51 based on the crystal structure of Mycobacterium tuberculosis Lehmann & Newman and docking with the azoles were performed. RESULTS: The affinity of the azoles for MGCYP51 was positively correlated with their hydrophobicity. Amino acid residues Tyr112, Phe120, Phe220, His308 and Phe497 of MGCYP51, forming a large hydrophobic cavity, are the key residues interacting with azole fungicides. Furthermore, Phe220 and Phe497 are fungus and species specific respectively. CONCLUSION: The results suggest that the more potent azole fungicides for MGCYP51 should possess more hydrophobic groups interacting with residues Phe220 and Phe497.