Adaptive [beta]-lactam resistance from an inducible efflux pump that is post-translationally regulated by the DjlA co-chaperone

• Published in: PLoS biology 2023-12, Vol.21 (12)
• Main Authors: Costafrolaz, Jordan, Panis, Gaël, Casu, Bastien, Ardissone, Silvia, Degeorges, Laurence, Pilhofer, Martin, Viollier, Patrick H
• Format: Article
• Language: English
• Subjects: Analysis; Beta lactamases; DNA-ligand interactions; Drug resistance in microorganisms; Gene expression; Methods; Molecular chaperones
• ISSN: 1544-9173
• DOI: 10.1371/journal.pbio.3002040

The acquisition of multidrug resistance (MDR) determinants jeopardizes treatment of bacterial infections with antibiotics. The tripartite efflux pump AcrAB-NodT confers adaptive MDR in the polarized [alpha]-proteobacterium Caulobacter crescentus via transcriptional induction by first-generation quinolone antibiotics. We discovered that overexpression of AcrAB-NodT by mutation or exogenous inducers confers resistance to cephalosporin and penicillin ([beta]-lactam) antibiotics. Combining 2-step mutagenesis-sequencing (Mut-Seq) and cephalosporin-resistant point mutants, we dissected how TipR uses a common operator of the divergent tipR and acrAB-nodT promoter for adaptive and/or potentiated AcrAB-NodT-directed efflux. Chemical screening identified diverse compounds that interfere with DNA binding by TipR or induce its dependent proteolytic turnover. We found that long-term induction of AcrAB-NodT deforms the envelope and that homeostatic control by TipR includes co-induction of the DnaJ-like co-chaperone DjlA, boosting pump assembly and/or capacity in anticipation of envelope stress. Thus, the adaptive MDR regulatory circuitry reconciles drug efflux with co-chaperone function for trans-envelope assemblies and maintenance.