Fig. 2: Convergent mutations in the co-evolved pylBCD genes.

A Locations of critical mutations identified in three subpopulations shown within the previously solved structures of M. barkeri B PylB (PDB: 3T7V), C PylC (PDB: 4FFP), and D PylD (PDB: 4J4B); amino acid substitutions were all found outside the enzyme active sites, with many PylB mutations resulting in increased cationic surface charge. Numbering scheme is based on the wild-type protein sequences of PylB, PylC, and PylD in Methanosarcina acetivorans. Specifically, numerical labels for PylB refer to the WT PylB protein sequence and do not include the 104 amino acids added by the SUMO tag. Brackets indicate residues naturally occurring in M. barkeri proteins that have diverged from the M. acetivorans sequence. Mutations highlighted in red were observed to be convergent across multiple subpopulations (for further mutation analysis of subpopulations, see Supplementary Tables 2 and 3).