[Structural disorder within the replicative complex of measles virus: functional implications]

Measles virus belongs to the Paramyxoviridae family within the Mononegavirales order. Its non segmented, single stranded, negative sense RNA genome is encapsidated by the nucleoprotein (N) to form a helical nucleocapsid. This ribonucleoproteic complex is the substrate for both transcription and replication. The RNA-dependent RNApolymerase (L) binds to the nucleocapsid template via its co-factor, the phosphoprotein (P). In this review, we summarize the main experimental data pointing out the abundance of structural disorder within measles virus N and P.We also describe studies indicating that structural disorder is a widespread property in the replicative complex of Paramyxoviridae and, more generally, of Mononegavirales. The functional implications of structural disorder are also discussed. Finally, we propose a model where the flexibility of the disordered N and P domains allows the formation of a tripartite complex (N̊-P-L) during replication, followed by the delivery of N monomers to the nascent genomic RNA chain.