Conclusions
Our results demonstrate that flexibility within the
residue 288–292 loop of poliovirus 3Dpol is needed
for completion of the enzyme's catalytic cycle, in
particular, the post-catalysis translocation step.
Mutations within the loop have drastic effects on
the activity of the polymerase, and a glycine is
required at position 289. These effects are likely due
to the disruption of a delicate balance of loop
conformations that must exist for proper function.
This loop exhibits high sequence and structural
conservation among viral polymerases, suggesting
that its conformational dynamics are a common