High level resistance to the antimicrobial peptide TAT-RasGAP (317-326) results from sequential acquisition of mutations influencing the Escherichia coli cell envelope biogenesis and composition

ABSTRACT: Antimicrobial peptides (AMPs) are promising alternatives to classical antibiotics against antibiotic-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. In this study, we analysed a strain of E. coli with extensive resistance to TAT-RasGAP (317-326) but not to other AMPs that we obtained after twenty passages during an in vitro resistance selection experiment. This strain accumulates four mutations, that all apparently affect bacterial envelope composition. One of these mutations is a point mutation in bamA, which encodes an essential protein involved in the folding and proper insertion of outer membrane proteins. The point mutation resulted in a charge change in an area of the protein corresponding to a negatively charged loop at the surface of BamA. Using CRISPR-Cas9-based targeted mutagenesis, we showed that mutations lowering the negative charge of this loop decreased sensitivity of E. coli to TAT-RasGAP (317-326). In silico simulations unveiled the molecular driving forces responsible for the interaction between TAT-RasGAP (317-326) and BamA. These results indicated that electrostatic interactions, particularly hydrogen bonds, are involved in the stability of the molecular complex, representing a predictive fingerprint of the TAT-RasGAP (317-326) - BamA interaction strength. Interestingly, BamA activity was not affected by TAT-RasGAP (317-326), indicating that BamA may function as a specific receptor for this AMP. 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 drug-resistant pathogens.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Escherichia Coli

SUBMITTER: Nicolas Jacquier  

LAB HEAD: Nicolas Jacquier

PROVIDER: PXD055766 | Pride | 2024-12-02

REPOSITORIES: Pride