title: First description of natural and experimental conjugation between Mycobacteria mediated by a linear plasmid.
abstract: BACKGROUND
  In a previous study, we detected the presence of a Mycobacterium avium species-specific insertion sequence, IS1245, in Mycobacterium kansasii. Both species were isolated from a mixed M. avium-M. kansasii bone marrow culture from an HIV-positive patient. The transfer mechanism of this insertion sequence to M. kansasii was investigated here.
  
  
  RESULTS
  A linear plasmid (pMA100) was identified in all colonies isolated from the M. avium-M. kansasii mixed culture carrying the IS1245 element. The linearity of pMA100 was confirmed. Other analyses suggested that pMA100 contained a covalently bound protein in the terminal regions, a characteristic of invertron linear replicons. Partial sequencing of pMA100 showed that it bears one intact copy of IS1245 inserted in a region rich in transposase-related sequences. These types of sequences have been described in other linear mycobacterial plasmids. Mating experiments were performed to confirm that pMA100 could be transferred in vitro from M. avium to M. kansasii. pMA100 was transferred by in vitro conjugation not only to the M. kansasii strain from the mixed culture, but also to two other unrelated M. kansasii clinical isolates, as well as to Mycobacterium bovis BCG Moreau.
  
  
  CONCLUSIONS
  Horizontal gene transfer (HGT) is one of most important mechanisms leading to the evolution and diversity of bacteria. This work provides evidence for the first time on the natural occurrence of HGT between different species of mycobacteria. Gene transfer, mediated by a novel conjugative plasmid, was detected and experimentally reproduced.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Michelle Christiane da Silva
authors.initials: MC
authors.lastname: Rabello
authors.forename: Cristianne Kayoko
authors.initials: CK
authors.lastname: Matsumoto
authors.forename: Luiz Gonzaga Paula de
authors.initials: LG
authors.lastname: Almeida
authors.forename: Maria Carmen
authors.initials: MC
authors.lastname: Menendez
authors.forename: Rosangela Siqueira de
authors.initials: RS
authors.lastname: Oliveira
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Silva
authors.forename: Maria Jesus
authors.initials: MJ
authors.lastname: Garcia
authors.forename: Sylvia Cardoso
authors.initials: SC
authors.lastname: Leão
mesh_terms: D018014:Gene Transfer Techniques; D022761:Gene Transfer, Horizontal; D009162:Mycobacterium avium / Q000235:genetics*; D009163:Mycobacterium bovis / Q000235:genetics; D019909:Mycobacterium kansasii / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D017421:Sequence Analysis