Structure-based rational screening of novel hit compounds with structural diversity for cytochrome P450 sterol 14alpha-demethylase from Penicillium digitatum.

Cytochrome P450 sterol 14alpha-demethylases (CYP51s) are essential enzymes in sterol biosynthesis and well-known as the target of antifungal drugs. All fungal CYP51s are integral membrane proteins, making structural and biophysical characterization more challenging. The X-ray crystallographic structure of CYP51 isolated from Mycobacterium tuberculosis (MT-CYP51) is the unique reported one hitherto. In the present study, a homology modeling three-dimensional structure of CYP51 from Penicillium digitatum (PD-CYP51) was generated by CPHmodels, in which the accuracy of sequence alignment could be improved by taking into account further structural conservation information, using MT-CYP51 as the template. Interaction mechanism between the active site of PD-CYP51 and its inhibitors were further investigated by molecular dynamics simulating and molecular docking. With the effective docking process and interaction analysis information, structure-based virtual screening was performed to pick out the thirty new potential inhibiting compounds with structural diversity by using a new virtual screening strategy including Flex-Pharm/PMF/GOLD//FlexX/PMF/GOLD molecular docking procedures, and finally, seven new hit compounds out of SPECs database with potent inhibitory ability were validated by bioaffinity assays at enzyme level and on P. digitatum in vitro. The positive results indicated that all modeling strategies and screening processes presented in the current study most like to be an encouraging way in search of novel lead compounds with structural diversity for the specifically individual fungal CYP51s of both plants and human pathogens in the future.