| Autor: |
Lanois-Nouri A; DGIMI, Univ Montpellier, INRAE, Montpellier, France., Pantel L; Nosopharm, Nîmes, France., Fu J; State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong Universitygrid.27255.37-Helmholtz Institute of Biotechnology, Qingdao, Shandong, China., Houard J; Nosopharm, Nîmes, France., Ogier JC; DGIMI, Univ Montpellier, INRAE, Montpellier, France., Polikanov YS; Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.; Department of Pharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois, USA., Racine E; Nosopharm, Nîmes, France., Wang H; State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Helmholtz International Lab for Anti-infectives, Shandong Universitygrid.27255.37-Helmholtz Institute of Biotechnology, Qingdao, Shandong, China., Gaudriault S; DGIMI, Univ Montpellier, INRAE, Montpellier, France., Givaudan A; DGIMI, Univ Montpellier, INRAE, Montpellier, France., Gualtieri M; Nosopharm, Nîmes, France. |
| Abstrakt: |
Antibiotic resistance is an increasing threat to human health. A direct link has been established between antimicrobial self-resistance determinants of antibiotic producers, environmental bacteria, and clinical pathogens. Natural odilorhabdins (ODLs) constitute a new family of 10-mer linear cationic peptide antibiotics inhibiting bacterial translation by binding to the 30S subunit of the ribosome. These bioactive secondary metabolites are produced by entomopathogenic bacterial symbiont Xenorhabdus ( Morganellaceae ), vectored by the soil-dwelling nematodes. ODL-producing Xenorhabdus nematophila symbionts have mechanisms of self-protection. In this study, we cloned the 44.5-kb odl biosynthetic gene cluster ( odl -BGC) of the symbiont by recombineering and showed that the N -acetyltransferase-encoding gene, oatA , is responsible for ODL resistance. In vitro acetylation and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses showed that OatA targeted the side chain amino group of ODL rare amino acids, leading to a loss of translation inhibition and antibacterial properties. Functional, genomic, and phylogenetic analyses of oatA revealed an exclusive cis -link to the odilorhabdin BGC, found only in X. nematophila and a specific phylogenetic clade of Photorhabdus . This work highlights the coevolution of antibiotic production and self-resistance as ancient features of this unique tripartite complex of host-vector-symbiont interactions without odl -BGC dissemination by lateral gene transfer. IMPORTANCE Odilorhabdins (ODLs) constitute a novel antibiotic family with promising properties for treating problematic multidrug-resistant Gram-negative bacterial infections. ODLs are 10-mer linear cationic peptides inhibiting bacterial translation by binding to the small subunit of the ribosome. These natural peptides are produced by Xenorhabdus nematophila, a bacterial symbiont of entomopathogenic nematodes well known to produce large amounts of specialized secondary metabolites. Like other antimicrobial producers, ODL-producing Xenorhabdus nematophila has mechanisms of self-protection. In this study, we cloned the ODL-biosynthetic gene cluster of the symbiont by recombineering and showed that the N -acetyltransferase-encoding gene, oatA , is responsible for ODL resistance. In vitro acetylation and LC-MS/MS analyses showed that OatA targeted the side chain amino group of ODL rare amino acids, leading to a loss of translation inhibition and antibacterial properties. Functional, genomic, and phylogenetic analyses of oatA revealed the coevolution of antibiotic production and self-resistance as ancient feature of this particular niche in soil invertebrates without resistance dissemination. |
