biostudies-literatureUnknown8(8)Garrett SRWellcome TrustBiotechnology and Biological Sciences Research CouncilThe type VII secretion system (T7SS) is found in many Gram-positive firmicutes and secretes protein toxins that mediate bacterial antagonism. Two T7SS toxins have been identified in <i>Staphylococcus aureus</i>, EsaD a nuclease toxin that is counteracted by the EsaG immunity protein, and TspA, which has membrane depolarising activity and is neutralised by TsaI. Both toxins are polymorphic, and strings of non-identical <i>esaG</i> and <i>tsaI</i> immunity genes are encoded in all <i>S. aureus</i> strains. To investigate the evolution of <i>esaG</i> repertoires, we analysed the sequences of the tandem <i>esaG</i> genes and their encoded proteins. We identified three blocks of high sequence similarity shared by all <i>esaG</i> genes and identified evidence of extensive recombination events beMicrobial genomicshttps://www.ebi.ac.uk/biostudies/studies/S-EPMC9484751biostudies-literatureHomologous recombination between tandem paralogues drives evolution of a subset of type VII secretion system immunity genes in firmicute bacteria.PMC9484751218622/Z/19/Z110183/A/15/ZBB/M011186/1101503/Z/13/ZPalmer TDicks JMariano GGarrett SRfalseHomologous recombination between tandem paralogues drives evolution of a subset of type VII secretion system immunity genes in firmicute bacteria.The type VII secretion system (T7SS) is found in many Gram-positive firmicutes and secretes protein toxins that mediate bacterial antagonism. Two T7SS toxins have been identified in <i>Staphylococcus aureus</i>, EsaD a nuclease toxin that is counteracted by the EsaG immunity protein, and TspA, which has membrane depolarising activity and is neutralised by TsaI. Both toxins are polymorphic, and strings of non-identical <i>esaG</i> and <i>tsaI</i> immunity genes are encoded in all <i>S. aureus</i> strains. To investigate the evolution of <i>esaG</i> repertoires, we analysed the sequences of the tandem <i>esaG</i> genes and their encoded proteins. We identified three blocks of high sequence similarity shared by all <i>esaG</i> genes and identified evidence of extensive recombination events be2022-01-01T00:00:00Z2022 Aug2026-05-27T11:15:24.043Z2024-12-04T07:50:37.449ZS-EPMC94847513596064210.1099/mgen.0.000868