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Updated: Aug 6, 2025

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
Published on: September 11, 2022
Delineation of a lactococcal conjugation system reveals a restriction-modification evasion system
Guillermo Ortiz Charneco1, Philip Kelleher1, Andrius Buivydas1
1School of Microbiology & APC Microbiome Ireland, University College Cork, Cork, Ireland.
Abstract:
Plasmid pUC11B is a 49.3-kb plasmid harboured by the fermented meat isolate Lactococcus lactis subsp. lactis UC11. Among other features, pUC11B encodes a pMRC01-like conjugation system and tetracycline-resistance. In this study, we demonstrate that this plasmid can be conjugated at high frequencies to recipient strains. Mutational analysis of the 22 genes encompassing the presumed pUC11B conjugation cluster revealed the presence of several genes with essential conjugation functions, as well as a gene, trsR, encoding a putative transcriptional repressor of this conjugation cluster. Furthermore, plasmid pUC11B encodes an anti-restriction protein, TrsAR, which facilitates higher conjugation frequencies when pUC11B is transferred into recipient strains containing Type II or Type III RM systems. These findings demonstrate how RM mechanisms can be circumvented when they act as a biological barrier for conjugation events.
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