Neither phosphorylation nor the amino-terminal part of rabies virus phosphoprotein is required for its oligomerization

Rabies virus (PV strain) phosphoprotein (P) was expressed in bacteria, This recombinant protein binds specifically to the nucleoprotein-RNA complex pu rified from infected cells. Chemical crosslinking and gel-filtration studie s indicated that the P protein forms oligomers. Analytical centrifugation d ata demonstrated the co-existence of monomeric and oligomeric forms of rabi es virus P protein and suggested that there is an equilibrium between these species. As P expressed in bacteria is not phosphorylated, this result ind icates that P phosphorylation is not required for its oligomerization. Alth ough an alignment of several rhabdovirus P sequences revealed that the amin oterminal domain of P has a conserved predicted propensity to form helical coiled coils, an aminoterminally truncated form of P protein, lacking the f irst 52 residues, was also shown to be oligomeric. Therefore, the amino-ter minal domain of rabies virus P is not necessary for its oligomerization.