Homologous recombination between tandem paralogues drives evolution of a subset of type VII secretion system immunity genes in firmicute bacteria

• DOI: 10.1099/mgen.0.000868
• Publication Date: 2022-08-12T16:17:06Z
• Authors: Stephen R. Garrett; Giuseppina Mariano; Jo Dicks; Tracy Palmer
• Keywords: Homology

The type VII secretion system (T7SS) is found in many Gram-positive firmicutes and secretes protein toxins that mediate bacterial antagonism. Two T7SS have been identified Staphylococcus aureus , EsaD a nuclease toxin counteracted by the EsaG immunity protein, TspA, which has membrane depolarising activity neutralised TsaI. Both are polymorphic, strings of non-identical esaG tsaI genes encoded all S. strains. To investigate evolution repertoires, we analysed sequences tandem their proteins. We three blocks high sequence similarity shared evidence extensive recombination events between paralogues facilitated through these conserved blocks. Recombination accounts for loss expansion genomes such during strains clonal complex 8. TipC, an TelC lipid II phosphatase secreted streptococcal T7SS, also multiple gene paralogues. locate to 5′ 3′ end tipC genes, strong Streptococcus mitis BCC08. By contrast, only single homology block across little intergenic within this family. conclude homologous one drivers clusters.