YfmR is a translation factor that prevents ribosome stalling and cell death in the absence of EF-P
Protein synthesis is performed by the ribosome and a host of highly conserved elongation factors. Elongation factor P (EF-P) prevents ribosome stalling at difficult-to-translate sequences, particularly  polyproline tracts. In bacteria, phenotypes associated with efp deletion range from modest to lethal, suggesting that some species encode an additional translation factor that has similar function to EF-P. Here we identify YfmR as a translation factor that is essential in the absence of EF-P in B. subtilis.  YfmR is an ABCF ATPase that is closely related to both Uup and EttA, ABCFs that bind the ribosomal E-site and are conserved in more than 50% of bacterial genomes. We show that YfmR associates with actively translating ribosomes, and that depleting YfmR from ?efp cells causes severe ribosome stalling at a polyproline tract in vivo. YfmR depletion from ?efp cells was lethal, and caused reduced levels of actively translating ribosomes. Our results therefore identify YfmR as an important translation factor that is essential in B. subtilis in the absence of EF-P. Overall design: Magellan 6x in vitro transposed gDNA prepared from wild-type B. subtilis 168 (40) was transformed into wild type or ?efp B. subtilis. Transposon insertions were sequenced on the Illumina MiSeq platform (v3 150 bp kit) at the Cornell University Biotechnology Resource Center.