The polymerase (L) protein of rinderpest virus interacts with the host cell protein striatin

Rinderpest virus (RPV) is a morbillivirus that causes a highly contagious disease affecting members of the order Artiodactyla. The viral L protein is the catalytic subunit of the RNA-dependent RNA polymerase. To search for host cell proteins with which L interacts, a library screen was performed using the yeast two-hybrid system. Several host cell proteins were recovered from the library screen as putative L-interactors; one of these was identified as striatin. A direct interaction between RPV L and striatin was confirmed using both co-immunoprecipitation assays and co-localisation studies using confocal microscopy. Striatin was also shown to co-localise with the RPV L protein in infected cells. The L proteins of morbilliviruses consist of three long highly conserved domains separated by short unconserved stretches of amino acids. The L domain with which striatin interacts was investigated by co-immunoprecipitation and striatin was shown to interact primarily with the central conserved domain.