Effects of single amino acid substitutions at the E residue in the conserved GDNE motif of the Nipah virus polymerase (L) protein

Summary Nipah virus (NiV) is an emergent zoonotic paramyxovirus. The L proteins of most paramyxoviruses contain a GDNQ motif, thought to be part of the catalytic site for polymerase activity. Conversely, NiV L has GDNE in this position. We substituted the E residue with eight different amino acid residues and examined the effect on L function in an in vitro replication assay. Our results demonstrated that NiV L functioned with similar efficiency with either GDNE or GDNQ, but polymerase activity was severely reduced or abolished when a structurally destabilising residue (such as K, P or G) was introduced at this site.