Structural Analyses of AC4 Protein of Sri Lankan Cassava Mosaic Virus

Abstract

RNA silencing is one of the important phenomenon in plant defense mechanism, it actively protect host plants against viral infections. Existing viruses must have developed counter defense strategies to survive this arms race. Such counter defense strategy is the viral silencing suppressor (VSRs) which have been reported to directly interfere with the various steps leading to the interference of viral RNAs. Most identified VSRs are multifunctional, besides being RNA-silencing suppressors, they often perform essential roles by functioning as coat proteins, helper components for viral transmission, replicases and movement proteins, proteases or transcriptional regulators. One such identified VSR is AC4 of Sri Lankan cassava mosaic virus strain. Trivial knowledge about the structure –function relationship of this VSR leads to this work, where we focus on the structure generation by modelling to identify the mode of interactions with the various effector molecules of the silencing pathways. Structural analyses have been performed to screen interacting residues. Results indicate conserved structural features which signify propensity of functional interactions and further shows that this VSR can be a potent tool for the analysis of RNA silencing mechanisms and the relationships between different silencing pathways and VSRs.