title: Transposition mechanism, molecular characterization and evolution of IS6110, the specific evolutionary marker of Mycobacterium tuberculosis complex.
abstract: The mycobacterial insertion sequence IS6110 proved crucial in deciphering tuberculosis (TB) transmission dynamics. This sequence was also shown to play an important role in the pathogenicity (transmission ability and/or virulence) of Mycobacterium tuberculosis, the main causative agent of TB in humans. In this study, we explored the usefulness of IS6110 and its potential as a phylogenetic/typing marker. We also analyzed the genetic polymorphism and evolutionary trends (selective pressure) of its transposase-encoding open reading frames (ORFs), A and B, using the maximum likelihood method. Both ORFs evolved chronologically through random single nucleotide polymorphisms. They were subjected to strict purifying selection more tight on orfA, with no evidence of significant recombination events. OrfA proved to have a crucial role in regulating the transpositional process. Several analyses showed that IS6110 acquisition antedated the emergence of the Mycobacterium tuberculosis complex. This original copy of IS6110 element was functionally optimal. In conclusion, this study not only demonstrated the usefulness of IS6110 in terms of phylogenetic and typing purposes and its transpositional mechanism, but also informed the scientific community on its evolutionary history.
authors.affiliation: Bacteriology Laboratory, Veterinary Research Institute of Tunisia, Institute for Scientific Agricultural Research, 20 rue Jabal Lakhdhar, 1006, La Rabta, Tunis, Tunisia. sarahthabetbenabdeljelil@gmail.com.
authors.forename: Sarah
authors.initials: S
authors.lastname: Thabet
authors.affiliation: Bacteriology Laboratory, Veterinary Research Institute of Tunisia, Institute for Scientific Agricultural Research, 20 rue Jabal Lakhdhar, 1006, La Rabta, Tunis, Tunisia.
authors.forename: Nada
authors.initials: N
authors.lastname: Souissi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics*; D019143:Evolution, Molecular; D005819:Genetic Markers / Q000235:genetics*; D016013:Likelihood Functions; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity; D016366:Open Reading Frames; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D019895:Transposases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005819:Genetic Markers; D019895:Transposases
keywords: Evolutionary marker; IS6110 insertion sequence; Mycobacterium tuberculosis; ORFs; Polymorphism; Selective pressure; Transposition