Phylogeny of Mycobacterium avium strains inferred from glycopeptidolipid biosynthesis pathway genes

Abstract

The Mycobacterium avium complex (MAC) encompasses two species, M. avium and Mycobacterium intracellulare, which are opportunistic pathogens of humans and animals. The standard method of MAC strain differentiation is serotyping based on a variation in the antigenic glycopeptidolipid (GPL) composition. To elucidate the relationships among M. avium serotypes a phylogenetic analysis of 13 reference and clinical M. avium strains from 8 serotypes was performed using as markers two genomic regions (890 bp of the gtfB gene and 2150 bp spanning the rtfA-mtfC genes) which are associated with the strains' serological properties. Strains belonging to three other known M. avium serotypes were not included in the phylogeny inference due to apparent lack of the marker sequences in their genomes, as revealed by PCR and Southern blot analysis. These studies suggest that serotypes prevalent in AIDS patients have multiple origins. In trees inferred from both markers, serotype 1 strains, known to have the simplest and shortest GPLs among all other serotypes, were polyphyletic. Likewise, comparisons of the inferred phylogenies with the molecular typing results imply that the existing tools used in epidemiological studies may be poor estimators of M. avium strain relatedness. Additionally, trees inferred from each marker had significantly incongruent topologies due to a well supported alternative placement of strain 2151, suggesting a complex evolutionary history of this genomic region.

Naturally occurring horizontal gene transfer and homologous recombination in Mycobacterium

“…Our recent phylogenetic analysis of M. avium strains using two closely linked markers, gtfB and rtfA-mtfC from the GPL biosynthesis gene cluster, unexpectedly revealed a potential horizontal transfer of one of the marker sequences between the strains belonging to different serotypes (Krzywinska et al, 2004). The notion of transfer was based on a well-supported alternative position of one of the strains (i.e.…”

“…In another study (Krzywinska et al, 2004) we performed a phylogenetic analysis of 13 M. avium strains using as markers two DNA fragments (a 926 bp fragment of the gtfB gene and a 2150 bp region spanning rtfA-mtfC genes; cf. Fig.…”

Altered expression profile of mycobacterial surface glycopeptidolipids following treatment with the antifungal azole inhibitors econazole and clotrimazole

“…For instance, they are the major glycolipids found within disseminated Mycobacterium avium-intracellulare complex (MAC) infections, the most common bacterial infection in AIDS patients (McNeil et al, 1987). The GPLs not only represent surrogate markers for mycobacterial species, such as Mycobacterium xenopi (Besra et al, 1993b;Riviere & Puzo, 1991), but also provide the basis for MAC serovariation (Krzywinska et al, 2004). GPLS are also found in saprophytic mycobacteria, such as Mycobacterium smegmatis, and in animal pathogens, such as M. avium paratuberculosis, Mycobacterium porcinum and Mycobacterium senegalense (Camphausen et al, 1988).…”

“…These apolar GPLs are termed the non-serovarspecific GPLs (nsGPLs) and are found in all members of the MAC and M. smegmatis (Aspinall et al, 1995;Belisle & Brennan, 1989;Brennan & Goren, 1979). The nsGPLs can be further extended with haptenic oligosaccharides linked to the 6-dTal to produce the highly antigenic serovarspecific GPLs (ssGPLs), which provide the basis for MAC serovariation (Krzywinska et al, 2004). Although the biosynthesis of the GPLs has not been fully elucidated, models for the synthesis of the lipopeptide core (Belisle et al, 1993a, b), its glycosylation (Billman- Jacobe et al, 1999) and its methylation (Eckstein et al, 2003) have been proposed.…”

Structure and Host Recognition of Serotype 13 Glycopeptidolipid from Mycobacterium intracellulare

“…However, it was difficult to distinguish serotypes 7, 12, and 13 by only serological and chromatographic techniques because of their structural similarity. The phylogeny of some MAIC strains based on GPL biosynthesis genes has been reported (23). In this study, the complete structure of the serotype 13 GPL was determined, and the genetic relationship between the serotype 7, 12, and 13 GPL biosynthesis was clarified.…”