Do simple sequence repeats in replication, repair and recombination genes of mycoplasmas provide genetic variability?

Simple sequence repeats (SSRs) or microsatellites are mono to hexa-nucleotide tandem repeats of DNA that are ubiquitous in intergenic regions and coding regions of genomes. SSRs may be essential for any genome as these repeats are found even in organisms like mycoplasmas (class Mollicutes) that have small genome size. Mollicutes cause different diseases in vertebrates including humans, insects and plants. Antibiotics have been developed against membrane proteins and replication related proteins like gyrase and topoisomerase. However, some pathogens have developed immunity against these drugs. Mycoplasmas can evade host immune response in which SSRs variations in membrane proteins play an important role. The present study seeks presence of dito penta-nucleotide repeats in genes associated with DNA replication, repair and recombination in thirteen mycoplasma genomes. Association of SSRs with these genes may have potential to provide variability for evading antibiotics against replication, repair and recombination proteins. In the present study SSRs are present in few genes but among the repeats found, maximum repeats are present in methylase, DNA polymerase, excinuclease and topoisomerase genes. Maximum number of repeat types are dinucleotides but present only in M. pulmonis. Pentanucleotide repeats are present in three mycoplasmas but tetranucleotide repeats are present in eight mycoplasmas.