Inhibition of Type IV secretion ATPase TrwD by unsaturated fatty acids as a potential tool to prevent wide spread dissemination of antibiotic resistance genes

Abstract

Antibiotic resistance has become a major health issue. Unfortunately, the development of new antibiotics is being very slow and expensive and we are running out of weapons to fi ght against the appearance of multi-resistant bugs. Bacterial conjugation is the main mechanism for the wide spread dissemination of antibiotic resistance genes and, therefore, the search of specific inhibitors of conjugation (COINs) could become a brand new strategy in this warfare. In the search of potential COINs, previous studies have reported that unsaturated fatty acids (uFAs) were able to inhibit conjugation. Based on these studies we have looked for the molecular targets of these compounds and we have found that the Type IV secretion ATPase TrwD is inhibited by linoleic acid and 2-alkynoic fatty acids, such as the 2-hexadecynoic acid. These two uFAs compounds were the most effective inhibitors in R388 plasmid conjugation. The inhibitory effect is specific for the traffic ATPase TrwD, as the remaining ATPases of the Type IV secretion system are unaffected by both uFAs and 2-AFAs. We have characterized the inhibition mechanism and we have found that in both cases it is a non-competitive inhibition, as the affinities for the substrate (ATP) and product (ADP) are not altered in the presence of the fatty acids. Altogether, these results could open new avenues in the development of new strategies to prevent the dissemination of antibiotic resistance genes.