In silico analysis for five major cereal crops phytocystatins

Five major cereal crops like rice, wheat, maize, barley and sorghum are continuously threatened by a multitude of pathogens and other disorders. Cystatins offers a pivotal role in deciding the promising plant response. The use of bioinformatics tools for phylogenetic relationships of five major cereal crops (rice, wheat, maize, barley and sorghum) phytocystatins based on amino acid sequence information was elucidated and their secondary and tertiary structures were investigated for structural comparisons. Twenty eight distinct phytocystatins from 28 plant species were investigated. Phytocystatins could be divided into five distinct phylogenetic groups. Five major cereal crops their structural features were highly conserved their amino acid sequence similarities ranged from 48 to 86%. A new highly conserved amino acid sequence motif, YEAKxWxKxF, in the C-terminal end being unique to phytocystatins was identified. The predicted 3D homology models showed a high conservation of the general central structure of the phytocystatins i.e. the 4-5 anti-parallel β-sheets, wrapping halfway round a single central α-helix and particularly the three active site regions, the N-terminal, the 1^st and 2^nd hairpin loops. Any structural differences seem to be mainly in the length of the N and C terminal, the length of the 2^nd hairpin loop and the 5^th β-sheet. Via docking experiments, small heterogeneities were observed in the vicinity of the OC-I active sites that seemed to be influential in the binding process and stability of the resultant inhibitor-protease complex.