title: Identification of a novel conjugative plasmid in mycobacteria that requires both type IV and type VII secretion.
abstract: Conjugative plasmids have been identified in a wide variety of different bacteria, ranging from proteobacteria to firmicutes, and conjugation is one of the most efficient routes for horizontal gene transfer. The most widespread mechanism of plasmid conjugation relies on different variants of the type IV secretion pathway. Here, we describe the identification of a novel type of conjugative plasmid that seems to be unique for mycobacteria. Interestingly, while this plasmid is efficiently exchanged between different species of slow-growing mycobacteria, including Mycobacterium tuberculosis, it could not be transferred to any of the fast-growing mycobacteria tested. Genetic analysis of the conjugative plasmid showed the presence of a locus containing homologues of three type IV secretion system components and a relaxase. In addition, a new type VII secretion locus was present. Using transposon insertion mutagenesis, we show that in fact both these secretion systems are essential for conjugation, indicating that this plasmid represents a new class of conjugative plasmids requiring two secretion machineries. This plasmid could form a useful new tool to exchange or introduce DNA in slow-growing mycobacteria.
  
  
  OBJECTIVE
  Conjugative plasmids play an important role in horizontal gene transfer between different bacteria and, as such, in their adaptation and evolution. This effect is most obvious in the spread of antibiotic resistance genes. Thus far, conjugation of natural plasmids has been described only rarely for mycobacterial species. In fact, it is generally accepted that M. tuberculosis does not show any recent sign of horizontal gene transfer. In this study, we describe the identification of a new widespread conjugative plasmid that can also be efficiently transferred to M. tuberculosis. This plasmid therefore poses both a threat and an opportunity. The threat is that, through the acquisition of antibiotic resistance markers, this plasmid could start a rapid spread of antibiotic resistance genes between pathogenic mycobacteria. The opportunity is that we could use this plasmid to generate new tools for the efficient introduction of foreign DNA in slow-growing mycobacteria.
authors.affiliation: Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Roy
authors.initials: R
authors.lastname: Ummels
authors.affiliation: Pathogen Genomics Group, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Abdallah M
authors.initials: AM
authors.lastname: Abdallah
authors.affiliation: Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Vincent
authors.initials: V
authors.lastname: Kuiper
authors.affiliation: Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Anouar
authors.initials: A
authors.lastname: Aâjoud
authors.affiliation: Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Marion
authors.initials: M
authors.lastname: Sparrius
authors.affiliation: Pathogen Genomics Group, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Raeece
authors.initials: R
authors.lastname: Naeem
authors.affiliation: Institute of Biology, Leiden University, Leiden, Amsterdam, The Netherlands.
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.affiliation: National Mycobacteria Reference Laboratory, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: van Soolingen
authors.affiliation: Pathogen Genomics Group, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
authors.forename: Arnab
authors.initials: A
authors.lastname: Pain
authors.affiliation: w.bitter@vumc.nl.
authors.forename: Wilbert
authors.initials: W
authors.lastname: Bitter
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D058947:Bacterial Secretion Systems / Q000235:genetics*; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D022761:Gene Transfer, Horizontal; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D058947:Bacterial Secretion Systems; D004269:DNA, Bacterial