Identification, cloning and bioinformatics analysis of the gene encoding NIa protein of wheat streak mosaic virus (WSMV)

Wheat streak mosaic virus (WSMV) is one of the most important wheat infectious which its prevalence is increasing in Iran. NIa protein as a key protein in WSMV, plays important roles in viral replication and proteolytic digestion of viral polyprotein. Considering the critical role of NIa protein in viral infection, isolation, sequencing and determination of secondary and tertiary structure of this protein were the objectives of the present study. Also, the amino acids present in the NIa protein active site, which can be used as the targets for design and developement of new antiviral agents, were investigated. In this study, the gene encoding NIa protein was isolated from WSMV and its sequencing was done followed by cloning in pEST prokaryotic vector. The resulted nucleotide sequence was deposited in NCBI database with accession number MK335432. Investigation of physical and chemical properties showed that NIa protein is including 426 amino acids, 48.8 kD molecular weight and 8.81 PI. Prediction of secondary structure of NIa protein revealed that 53.29% of its structure composed of irregular loops, which was justified by the structural dirsorder of this protein. The results of the active site investigation of NIa protein based on homologous sequences alignment and three-dimensional structure of the protein showed a highly conserved site which was included of histidine, aspartic acid and cysteine amino acids.