GP2 and infection: To obtain further experimental evidence that E24K and F27Y substitutions in Gp2 facilitate the interaction of Gp2 with RNAp when the primary interaction interface with the β′ jaw domain is compromised, we conducted experiments with Gp2 homologues, proteins 13 and 16 from phages CR44b and CR8 (CR44b_13 and CR8_16), which infect C. rodentium, a model animal bacterial pathogen used to study human infections by enteropathogenic and enterohaemorrhagic E. coli.