Functional Importance of the Hydrophobic Residue 362 in Influenza A PB1 Subunit

PB1, acting as the catalytic subunit of the influenza polymerase, has numerous sequentially and structurally conserved regions. It has been observed that the slight modification of residues in PB1 would greatly affect the polymerase activity and even host adaptation ability. Here, we identified a critical residue, 362M, on the polymerase activity and virus replication. By means of the minireplicon assay, we assured the importance of the hydrophobicity of PB1 362, and the possibility that the size and charge of the side chain might directly interfere with the polymerase function. We also proposed a hydrophobic core between the PA-arch and the PB1 beta-hairpin motifs and showed the importance of the core to the polymerase function.

Automated summary

PB1, as the catalytic subunit of the influenza polymerase, has conserved regions. A critical residue, 362M, on PB1 has been identified to affect polymerase activity and virus replication. Hydrophobicity and the size and charge of the side chain of PB1 362 were found to be important for polymerase function. A hydrophobic core between the PA-arch and the PB1 beta-hairpin motifs was proposed and shown to be important for polymerase function.