Viral gain-of-function experiments uncover residues under diversifying selection in nature

Rohan Maddamsetti; Daniel T. Johnson; Stephanie J. Spielman; Katherine L. Petrie; Debora S. Marks; Justin R. Meyer

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/242495 doi: bioRxiv preprint baseline, and random combinations of 19 other J mutations found in the OmpF + l evolved by Meyer et al. (2012) . Screening this second library produced 88 OmpF + isolates. One OmpF + isolate had just a single extra mutation in amino acid position 1083 in addition to the three canonical mutations (Figure 1 ). However, the majority of the OmpF + genotypes did not possess this specific mutation, signifying that its function could be substituted by other J mutations. In total, this experiment revealed that four mutations are sufficient to evolve the innovation, but only two specific amino acid changes (at residues 1012 and 1107) are universally required to access OmpF in the context of laboratory experiments.