Eeyarestatin 24 Impairs SecYEG-dependent Protein Trafficking and Inhibits Growth of Clinically Relevant Pathogens

Eeyarestatin 1 (ES1) is an inhibitor of endoplasmic reticulum (ER) associated protein degradation, Sec61-dependent Ca2+ homeostasis and protein translocation into the ER. Recently, evidence was presented showing that a smaller analogue of ES1, ES24, targets the Sec61-translocon and captures it in an open conformation that is translocation-incompetent. We now show that ES24 impairs protein secretion and membrane protein insertion in Escherichia coli via the homologous SecYEG translocon. Transcriptomic analysis suggested that ES24 has a complex mode of action, probably involving multiple targets. Interestingly, ES24 shows anti-bacterial activity towards clinically relevant strains. Furthermore, the anti-bacterial activity of ES24 is equivalent to or better than that of nitrofurantoin, a known antibiotic that, although structurally similar to ES24, does not interfere with SecYEG-dependent protein trafficking. Like nitrofurantoin, we find that ES24 requires activation by the NfsA and NfsB nitroreductases, suggesting that the formation of highly reactive nitroso intermediates is essential for target inactivation in vivo.