Abstract
Within the larger ABC superfamily of ATPases, ABCF family members eEF3 in Saccharomyces cerevisiae and EttA in Escherichia coli have been characterised as ribosomal translation factors. Several other ABCFs including VgaA and LsaA confer resistance to MLS-type ribosome-targeting antibiotics. However, the diversity of ABCF subfamilies, the relationships among subfamilies and the evolution of antibiotic resistance factors from other ABCFs have not been explored. To address this, we analysed the presence of ABCFs and their domain architectures in 4505 genomes across the tree of life. We find that there are 45 distinct subfamilies of ABCFs, which are widespread across bacterial and eukaryotic phyla, suggesting they were present in the last common ancestor of both. Surprisingly, currently known antibiotic resistance (ARE) ABCFs are not confined to a distinct lineage of the ABCF family tree. This suggests that either antibiotic resistance is a general feature of bacterial ABCFs, or it is relatively easy to evolve antibiotic resistance from other ABCF functions. While eEF3 was thought to be fungi-specific, we have found eEF3-like factors in a range of single celled eukaryotes, suggesting an ancient origin in this domain of life. Finally, we address ribosome association of the four E. coli ABCFs EttA, YbiT, YheS and Uup through polysome profiling combined with Western blot detection, as well as 35S-methionine pulse labeling assays upon expression of the ATPase deficient ABCF mutants.
