Sumoylation of Human Parainfluenza Virus Type 3 Phosphoprotein Correlates with A Reduction in Viral Replication

Human parainfluenza virus type 3(HPIV3), a member of the Paramyxoviridae family, can cause lower respiratory disease in infants and young children. The phosphoprotein(P) of HPIV3 is an essential cofactor of the viral RNA-dependent RNA polymerase large protein(L). P connects nucleocapsid protein(N) with L to initiate genome transcription and replication.Sumoylation influences many important pathways of the target proteins, and many viral proteins are also themselves sumoylated. In this study, we found that the P of HPIV3 could be sumoylated, and mutation of K492 and K532 to arginine(PK492 R/K532 R) failed to be sumoylated within P, which enhances HPIV3 minigenome activity. Biochemical studies showed that PK492 R/K532 Rhad no effect on its interactions with N, formation of homo-tetramers and formation of inclusion bodies.Finally, we found that incorporation of K492 R/K532 R into a recombinant HPIV3(rHPIV3-PK492 R/K532 R) increased viral production in culture cells, suggesting that sumoylation attenuates functions of P and down-regulates viral replication.