Molecular analysis of an integrative conjugative element, ICEH, present in the chromosome of different strains of Mycoplasma hyopneumoniae

Abstract

Diversification of bacterial species and pathotypes is largely caused by lateral gene transfer (LGT) of diverse mobile DNA elements such as plasmids, phages, transposons and genomic islands. Thus, acquisition of new phenotypes by LGT is very important for bacterial evolution and relationship with hosts. This paper reports a 23 kb region containing fourteen CDSs with similarity to the previous described Integrative Conjugal Element of Mycoplasma fermentans (ICEF). This element, named ICEH, is present as one copy at distinct integration sites in the chromosome of 7448 and 232 pathogenic strains and is absent in the type strain J (non-pathogenic). Notable differences in the nucleotide composition of the insertion sites were detected, and could be correlated to a lack of specificity of the ICEH integrase. Although present in strains of the same organism, the ICEH elements are more divergent than the typical similarity between other chromosomal locus of Mycoplasma hyopneunomiae, suggesting an accelerated evolution of these constins or an ongoing process of degeneration, while maintaining conservation of the tra genes. An extrachromosomal form of this element had been detected in the 7448 strain, suggesting a possible involvement in its mobilization and transference of CDSs to new hosts.

Comparative genomic analyses of Mycoplasma hyopneumoniae pathogenic 168 strain and its high-passaged attenuated strain

“…The ICEH elements are more divergent than the typical similarity of other chromosomal locus in M. hyopneunomiae [25], suggesting an accelerated evolution of these constins [26]. During a survey of specific sequences, a specific 26.9-kb region with similarity to the integrative conjugal element of M. fermentans (ICEF) [27] was found in strain 168, which was designated ICEH (for integrative conjugal element of M. hyopneumoniae ).…”

“…The organization of these elements is very similar. Some CDSs present similarity to tra genes, which are usually associated with the bacteria conjugative plasmids such as traK , traI , traE [26] . The ICEH168 has three tra genes, with one traG and two copies of the traE gene.…”

“…The ICE analysis of three M. hyopneumoniae genomes (7448, J and 232) carried out previously, revealed that the ICEH is present in the two pathogenic strains (7448 and 232) but is absent from the non-pathogenic one (J strain) [26]. Interest has therefore shifted to questions of whether the ICEH is present in the attenuated vaccine strain 168-L. Interestingly, the ICEH was also observed in strain 168-L.…”

Update onMycoplasma hyopneumoniaeinfections in pigs: Knowledge gaps for improved disease control

“…An integrative conjugal element (ICE) has been identified in the genomes of pathogenic strains 7448 and 232, while it is absent in the non-pathogenic strain J (Pinto, de Carvalho, Alves-Junior, Brocchi, & Schrank, 2007). The ICE from M. hyopneumoniae, called ICEH, was also found in the pathogenic strain 168 but likewise in its attenuated variant (Liu et al, 2013).…”

The Integrative Conjugative Element (ICE) ofMycoplasma agalactiae: key elements involved in horizontal dissemination and influence of co-resident ICEs

“…CDS14 lipoprotein expression in 5632 that contains three chromosomal ICEA copies (1) was not abrogated in a 5632 mutant harboring a cds14 knockout ICEA copy (2). CDS14 lipoprotein expression can be detected in PG2 transconjugants having acquired a mutant ICEA harboring a mTn inserted in ncr19/E (4), but not in PG2 (3) or PG2 transconjugants harboring a cds14 knock-out ICEA (5). Transformation of PG2 transconjugants harboring a cds14 knock-out ICEA with a plasmid expressing CDS14 restored the expression of the lipoprotein (6).…”