Fungal Mannosyltransferase as a target to control Magnaporthe oryzae through natural bioactive compounds – A bioinformatics approach

Abstract

Magnaporthe oryzae is a filamentous ascomycete fungus and causes a polycyclic disease called rice blast, which causes the farmers approximately 10 to 30% yield loss. Along with chitin, Glycans are important components of a fungal cell wall, and disruption of them results in compromising the fungal cell integrity. The inhibition of mannosyltransferase is one of the key enzymes involved in the biosynthesis of glycans, which compromises cell wall development and prevents the spread of the disease. The homology-modelled structure of mannosyltransferase was docked against nine natural bioactive compounds from Annona Squamosa, Azadirachta Indica and Curcuma longa, from among which Anonaine from A. squamosa recorded the highest docking score of -8.2. This complex was subjected to in-silico molecular dynamic simulation (MDS) using GROMACS. During molecular dynamic simulations, post 60 ns, the RMSD value was observed to settle down to 0.8 nm. The plot suggests that the protein acquired stable confirmation post 60 ns without much fluctuation. The majority of the residues of mannosyltransferase showed RMSF less than 0.3 nm. 2 peaks were observed in 100 ns simulation, from 200 to 230 residues and 280 to 300 residues where the RMSF value is greater than 0.3 nm, which indicates that these regions are flexible. The MDS results show that the complex is stable and can form under natural conditions. Our in silico docking studies and MDS revealed anonaine from A. squamosa as one of the natural compounds capable of binding to mannosyltransferase, which thereby may compromise the assembly of one of the major components of the fungal cell wall, i.e. Glucans.