Surface exclusion of IncC conjugative plasmids and their relatives.

Autor: Rivard N; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada., Humbert M; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada., Huguet KT; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada., Fauconnier A; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada., Bucio CP; Instituto Tecnológico y de Estudios Superiores de Monterrey, Monterrey, Nuevo León, Mexico., Quirion E; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada., Burrus V; Département de biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Jazyk: angličtina
Zdroj: PLoS genetics [PLoS Genet] 2024 Oct 09; Vol. 20 (10), pp. e1011442. Date of Electronic Publication: 2024 Oct 09 (Print Publication: 2024).
DOI: 10.1371/journal.pgen.1011442
Abstrakt: The phenomenon of exclusion allows conjugative plasmids to selectively impede the entry of identical or related elements into their host cell to prevent the resulting instability. Entry exclusion blocks DNA translocation into the recipient cell, whereas surface exclusion destabilizes the mating pair. IncC conjugative plasmids largely contribute to the dissemination of antibiotic-resistance genes in Gammaproteobacteria. IncC plasmids are known to exert exclusion against their relatives, including IncC and IncA plasmids, yet the entry exclusion factor eexC alone does not account for the totality of the exclusion phenotype. In this study, a transposon-directed insertion sequencing approach identified sfx as necessary and sufficient for the remaining exclusion phenotype. Sfx is an exclusion factor unrelated to the ones described to date. A cell fractionation assay localized Sfx in the outer membrane. Reverse transcription PCR and beta-galactosidase experiments showed that sfx is expressed constitutively at a higher level than eexC. A search in Gammaproteobacteria genomes identified Sfx homologs encoded by IncC, IncA and related, untyped conjugative plasmids and an uncharacterized family of integrative and mobilizable elements that likely rely on IncC plasmids for their mobility. Mating assays demonstrated that sfx is not required in the donor for exclusion, ruling out Sfx as the exclusion target. Instead, complementation assays revealed that the putative adhesin TraN in the donor mediates the specificity of surface exclusion. Mating assays with TraN homologs from related untyped plasmids from Aeromonas spp. and Photobacterium damselae identified two surface exclusion groups, with each Sfx being specific of TraN homologs from the same group. Together, these results allow us to better understand the apparent incompatibility between IncA and IncC plasmids and to propose a mechanistic model for surface exclusion mediated by Sfx in IncC plasmids and related elements, with implications for the rampant dissemination of antibiotic resistance.
Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: V.B. has served as guest editor in 2021/2022 for PLoS Genetics. All other authors have no competing interest.
(Copyright: © 2024 Rivard et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
Databáze: MEDLINE
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