N-terminal region of P protein of Chandipura virus is responsible for phosphorylation-mediated homodimerization

The phosphoprotein P of Chandipura (CHP) virus, an Indian isolate of rhabdovirus, was found to support transcription upon phosphorylation by casein kinase II (CKII). A phosphorylation-induced change in the protein conformation was found to occur at the N-terminal region of the protein. Biochemical studies for further characterization of this phosphorylation-based conformational alteration demonstrated that phosphorylation leads to the transition from an `open' to `closed' structure of the protein. The phosphate group introduced by CKII was found to be resistant to phosphatases. This phosphorylation-based structural alteration changes the accessible hydrophobic surface area of the protein and also the available digestion sites of different proteases. The phosphorylated form of P protein was found to be a dimer by His-tag dilution assay. Using the same approach it was found that the N-terminal 46 amino acids are responsible for P–P dimerization, only after phosphorylation