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Abstract

Background: The PE and PPE multigene families of Mycobacterium tuberculosis comprise about 10% of the coding potential of the genome. The function of the proteins encoded by these large gene families remains unknown, although they have been proposed to be involved in antigenic variation and disease pathogenesis. Interestingly, some members of the PE and PPE families are associated with the ESAT-6 (esx) gene cluster regions, which are regions of immunopathogenic importance, and encode a system dedicated to the secretion of members of the potent T-cell antigen ESAT-6 family. This study investigates the duplication characteristics of the PE and PPE gene families and their association with the ESAT-6 gene clusters, using a combination of phylogenetic analyses, DNA hybridization, and comparative genomics, in order to gain insight into their evolutionary history and distribution in the genus Mycobacterium.

Insights from the complete genome sequence of Mycobacterium marinum on the evolution of Mycobacterium tuberculosis

“…A summary of the average percent amino acid identity for these core CDS is presented in Supplemental Table 4 and was used to infer a phylogeny (Fig. 3B) that demonstrates M. marinum is most closely related to M. ulcerans and then to M. tuberculosis (3000 shared orthologs) and least related to M. smegmatis, a phylogeny in close agreement with those based on 16S rRNA gene sequences (Gey van Pittius et al 2006).…”

“…Compared with 115 in M. ulcerans and 169 in M. tuberculosis, M. marinum has the most extensive repertoire yet reported of these mycobacteria-specific proteins representing 9.1% of its coding capacity, compared with 7.1% for M. tuberculosis and 3.8% for M. ulcerans. It has been proposed that the PE/PPE genes coevolved with the ESX loci and then underwent a specific and significant expansion in the common progenitor of M. tuberculosis, M. marinum, and M. ulcerans (Gey van Pittius et al 2006). Such a large collection of these genes in M. marinum may be consistent with its diverse host range as some PE-PGRS proteins from M. marinum are known to be involved in intracellular persistence (Ramakrishnan et al 2000).…”

“…Such a large collection of these genes in M. marinum may be consistent with its diverse host range as some PE-PGRS proteins from M. marinum are known to be involved in intracellular persistence (Ramakrishnan et al 2000). Significant amino acid sequence divergence occurs, predominantly within the C-terminal region of these proteins (Garnier et al 2003;Gey van Pittius et al 2006), suggesting that they are subject to constant diversifying selection, perhaps to avoid detection or destruction during intracellular life in a variety of hosts.…”

“…Several phylogenetic studies have shown that M. marinum is most closely related to Mycobacterium ulcerans (>97% nucleotide identity) and then M. tuberculosis (>85% nucleotide identity) (Tønjum et al 1998;Stinear et al 2000;Devulder et al 2005;Gey van Pittius et al 2006;Yip et al 2007). Multi-locus sequence typing (MLST) and the recently completed M. ulcerans genome sequence clearly show that M. ulcerans has recently evolved from a M. marinum progenitor by acquisition of a virulence plasmid and reductive evolution (Stinear et al 2004Yip et al 2007).…”

Effect of Environmental Stresses on Growth Pattern, Biofilm Formation and Biochemical Characteristics of Mycobacterium marinum CCUG20998

“…fish and frogs. The infections caused by M. marinum in warm-blooded hosts, such as human, and poikilothermic animals, such as fishes and frogs, is indistinguishable with the infection caused by M .tuberculosis complex [4,5]. In comparison to M. tuberculosis, M. marinum grows with a relatively short doubling time and growth is limited at higher temperatures, making M. marinum easier to handle than e.g.…”