E. coli acquires specific resistance to the antimicrobial peptide TAT-RasGAP (317-326) via modification of charge at the surface of the essential outer membrane insertase BamA

ABSTRACT: Antimicrobial peptides (AMPs) are promising alternatives to classical antibiotics against multidrug resistant pathogens. TAT-RasGAP (317-326) is an AMP with broad range antibacterial activity, but its mechanism of action is unknown. Escherichia coli can become partially resistant to TAT-RasGAP (317-326) in vitro when passaged eight times with increasing concentrations of this peptide via mutations of the two-component system EnvZ/OmpR. To test whether additional mutations can cause further increase in resistance, we analysed a strain of E. coli showing high level of specific resistance to TAT-RasGAP (317-326) that we obtained after twenty passages of in vitro resistance selection. This strain bears, in addition to an envZ point mutation, a point mutation in bamA, an essential gene encoding an insertase involved in the insertion of outer membrane proteins. This mutation modifies the charge in a negatively charged loop (Q495-T505) at the surface of BamA. In silico docking simulations predict that binding affinity between TAT-RasGAP (317-326) and BamA varies depending on the charge of the Q495-T505 loop. We show here using CRISPR-Cas9-based targeted mutagenesis that mutations lowering the negative charge of the Q495-T505 loop decrease sensitivity of E. coli to TAT-RasGAP (317-326). Interestingly, BamA activity was not affected by TAT-RasGAP (317-326), indicating that BamA may function as a specific receptor for the AMP TAT-RasGAP (317-326). Our results indicate that binding and entry of TAT-RasGAP (317-326) may involve different mechanisms compared to other AMPs, which is in line with limited cross-resistance observed between different AMPs. This limited cross-resistance is important for the clinical application of AMPs towards multidrug resistant pathogens.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Escherichia Coli

SUBMITTER: Nicolas Jacquier  

LAB HEAD: Nicolas Jacquier

PROVIDER: PXD051962 | Pride | 2024-12-02

REPOSITORIES: Pride