Abstract : The polymerase of negative-stranded RNA viruses consists of the large protein (L) and the phosphoprotein (P), the latter serving both as a chaperon and a cofactor for L. We mapped within measles virus (MeV) P the regions responsible for binding and stabilizing L and showed that the coiled-coil multimerization domain (MD) of P is required for gene expression. MeV MD is kinked as a result of the presence of a stammer. Both restoration of the heptad regularity and displacement of the stammer strongly decrease or abrogate activity in a minigenome assay. By contrast, P activity is rather tolerant of substitutions within the stammer. Single substitutions at the “a” or “d” hydrophobic anchor positions with residues of variable hydrophobicity revealed that P functionality requires a narrow range of cohesiveness of its MD. Results collectively indicate that, beyond merely ensuring P oligomerization, the MD finely tunes viral gene expression through its cohesiveness.

Source: Regulation of measles virus gene expression by P protein coiled coil properties. Bloyet, L.M., Schramm, A.,  Lazert, Raynal, C.B., Hologne, M., Walker, O., Longhi,S. Gerlier, D. Science Advances; 8 May  Vol. 5, No. 5 DOI: 10.1126/sciadv.aaw3702