A-to-I mRNA editing enables bacteria to produce two protein versions from a single gene and affects bacterial growth

Adenosine-to-inosine (A-to-I) mRNA editing can affect the sequence and function of translated proteins because the ribosome reads inosine (I) as guanosine (G). Previously, we discovered that A-to-I mRNA editing occurs in Escherichia coli. However, the prevalence of A-to-I mRNA editing across bacteria and its biological significance are still unknown. Here, we show that A-to-I mRNA editing occurs in hundreds of genes across dozens of bacterial species. We find that editing events occur within and require a conserved sequence motif. Notably, most editing events (80%) are predicted to recode protein sequences. Indeed, by mass spectrometry, we show for the first time that A-to-I mRNA editing enables bacteria to produce two versions of a protein from a single gene. Finally, we find that perturbing mRNA editing in Acinetobacter baylyi affects bacterial growth, especially at high temperatures. Overall, our work reveals that A-to-I mRNA editing is widespread and can impact bacterial physiology, likely by modulating protein function