Mycoplasma mycoides, from "mycoides Small Colony" to "capri". A microevolutionary perspective

Abstract

BackgroundThe Mycoplasma mycoides cluster consists of five species or subspecies that are ruminant pathogens. One subspecies, Mycoplasma mycoides subspecies mycoides Small Colony (MmmSC), is the causative agent of contagious bovine pleuropneumonia. Its very close relative, Mycoplasma mycoides subsp. capri (Mmc), is a more ubiquitous pathogen in small ruminants causing mastitis, arthritis, keratitis, pneumonia and septicaemia and is also found as saprophyte in the ear canal. To understand the genetics underlying these phenotypic differences, we compared the MmmSC PG1 type strain genome, which was already available, with the genome of an Mmc field strain (95010) that was sequenced in this study. We also compared the 95010 genome with the recently published genome of another Mmc strain (GM12) to evaluate Mmc strain diversity.ResultsThe MmmSC PG1 genome is 1,212 kbp and that of Mmc 95010 is ca. 58 kbp shorter. Most of the sequences present in PG1 but not 95010 are highly repeated Insertion Sequences (three types of IS) and large duplicated DNA fragments. The 95010 genome contains five types of IS, present in fewer copies than in PG1, and two copies of an integrative conjugative element. These mobile genetic elements have played a key role in genome plasticity, leading to inversions of large DNA fragments. Comparison of the two genomes suggested a marked decay of the PG1 genome that seems to be correlated with a greater number of IS. The repertoire of gene families encoding surface proteins is smaller in PG1. Several genes involved in polysaccharide metabolism and protein degradation are also absent from, or degraded in, PG1.ConclusionsThe genome of MmmSC PG1 is larger than that of Mmc 95010, its very close relative, but has less coding capacity. This is the result of large genetic rearrangements due to mobile elements that have also led to marked gene decay. This is consistent with a non-adaptative genomic complexity theory, allowing duplications or pseudogenes to be maintained in the absence of adaptive selection that would lead to purifying selection and genome streamlining over longer evolutionary times. These findings also suggest that MmmSC only recently adapted to its bovine host.

Genome Analysis of a Mycoplasma hyorhinis Strain Derived from a Primary Human Melanoma Cell Line

“…Unlike recent data on M. mycoides (12), no function-specific LCBs were identified. The MAUVE progressive mode utilized to identify conserved large segments revealed that each chromosome was composed of 4 regions and that differences may be explained by 2 inversions (14.4 kb, SRH_02645 to SRH_02545, and 3.7 kb, SRH_2605 to SRH_2635).…”

Molecular cloning and immune response analysis of putative variable lipoproteins from Mycoplasma mycoides subsp capri

“…It facilitates the studies on the molecular basis and pathogenic mechanisms of infection by members of the M. mycoides cluster. Comparative genomic analysis illustrates high genomic plasticity and their very close relatedness (Thiaucourt et al, 2011;Fischer et al, 2012).…”

“…Vmc and vmm, variable lipoproteins genes of Mycoplasma capricolum subsp capricolum (Mcc) and MmmSC, respectively, encode distinct variable lipoproteins (Persson et al, 2002;Wise et al, 2006). A cluster of genes in the Mmc strain 95010 genome (MLC_9030;9040;9050;9070;9080;9090) and Mmc strain GM12 genome (MMCAP2_0900 to 0904) sharing sequence similarities with vmc may encode variable lipoproteins according to annotation (Thiaucourt et al, 2011). On the basis of comparative genomic analysis of Mycoplasma leachii (Ml) str.…”

“…The functions of these motifs are unknown. Maybe repeat count variation of poly AA tracts (or poly TA tracts) regulates gene expression by affecting the interaction between promoters and RNA polymerase (Le et al, 1996;Zhang and Wise, 1997;Washburn et al, 1998;Persson et al, 2002;Wise et al, 2006;Thiaucourt et al, 2011).…”

Complete Genome Sequences of Mycoplasma leachii Strain PG50 T and the Pathogenic Mycoplasma mycoides subsp. mycoides Small Colony Biotype Strain Gladysdale

“…ontagious bovine pleuropneumonia (CBPP) is among the most important blights of cattle in countries in which CBPP is endemic (8). Although the study of the etiologic agent, Mycoplasma mycoides subsp.…”