EF-P dependent genes in Salmonella Typhimurium

Elongation factor P (EF-P) is required to enhance peptidyl transferase on pausing ribosomes, which can be induced by certain codons on mRNA. It regulates expression of genes in specific conditions. Therefore, to search EF-P mediated ribosome stalling motif, ribosome profiling has been used on organisms such as yeast and E. coli. However, it has not been addressed on the intracellular pathogen Salmonella Typhimurium. Through the ribosome profiling, 135 sites in 128 genes were identified as EF-P dependent sequences and many of these sites had consecutive proline codons specifically at P site of the ribosome. As a motif level, PPG was the most abundant amino acid sequence at EPA site of the ribosome and followed by APP and DPP sequence. Also, our findings revealed that salmonella-specific gene, ugtL, is regulated by frameshifting caused during translation as ribosome stalled in the DPP motif. In addition, we showed that both proline motif and EF-P are engaged in this regulation, and it affects the resistance to antimicrobial peptides. In conclusion, this study emphasized the importance of poly proline motif on EF-P and suggested a possible mechanism how EF-P affects the physiology of Salmonella. To investigate EF-P mediated ribosome stalling motif and its relevance on the virulence of S. Typhimurium, we conducted ribosome profiling in wild-type and efp strain and found genes that are regulated by EF-P.