The mechanisms underlying antigenic variation and maintenance of genomic integrity inMycoplasma pneumoniaeandMycoplasma genitalium

Mycoplasma pneumoniaeandMycoplasma genitaliumare important causative agents of infections in humans. Like all other mycoplasmas, these species possess genomes that are significantly smaller than that of other prokaryotes. Moreover, both organisms possess an exceptionally compact set of DNA recombination and repair-associated genes. These genes, however, are sufficient to generate antigenic variation by means of homologous recombination between specific repetitive genomic elements. At the same time, these mycoplasmas have likely evolved strategies to maintain the stability and integrity of their 'minimal' genomes. Previous studies have indicated that there are considerable differences between mycoplasmas and other bacteria in the composition of their DNA recombination and repair machinery. However, the complete repertoire of activities executed by the putative recombination and repair enzymes encoded byMycoplasmaspecies is not yet fully understood. In this paper, we review the current knowledge on the proteins that likely form part of the DNA repair and recombination pathways of two of the most clinically relevantMycoplasmaspecies,M. pneumoniaeandM. genitalium.The characterization of these proteins will help to define the minimal enzymatic requirements for creating bacterial genetic diversity (antigenic variation) on the one hand, while maintaining genomic integrity on the other.

Automated summary

Mycoplasma pneumoniae and Mycoplasma genitalium are important causative agents of infections in humans, with genomes smaller than other prokaryotes and compact DNA recombination and repair-associated genes. These organisms generate antigenic variation through homologous recombination and likely have strategies to maintain the stability of their genomes. Previous studies have shown differences in the DNA recombination and repair machinery of mycoplasmas compared to other bacteria, but the complete activities of the enzymes encoded by Mycoplasma species are not fully understood. Characterizing these proteins may help define the minimal enzymatic requirements for creating bacterial genetic diversity while preserving genomic integrity.