title: Conjugation in Gram-Positive Bacteria.
abstract: Conjugative transfer is the most important means of spreading antibiotic resistance and virulence factors among bacteria. The key vehicles of this horizontal gene transfer are a group of mobile genetic elements, termed conjugative plasmids. Conjugative plasmids contain as minimum instrumentation an origin of transfer (oriT), DNA-processing factors (a relaxase and accessory proteins), as well as proteins that constitute the trans-envelope transport channel, the so-called mating pair formation (Mpf) proteins. All these protein factors are encoded by one or more transfer (tra) operons that together form the DNA transport machinery, the Gram-positive type IV secretion system. However, multicellular Gram-positive bacteria belonging to the streptomycetes appear to have evolved another mechanism for conjugative plasmid spread reminiscent of the machinery involved in bacterial cell division and sporulation, which transports double-stranded DNA from donor to recipient cells. Here, we focus on the protein key players involved in the plasmid spread through the two different modes and present a new secondary structure homology-based classification system for type IV secretion protein families. Moreover, we discuss the relevance of conjugative plasmid transfer in the environment and summarize novel techniques to visualize and quantify conjugative transfer in situ.
authors.affiliation: Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Goessweiner-Mohr
authors.affiliation: Robert Koch-Institute, Nordufer 20, 13353 Berlin, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Arends
authors.affiliation: Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Keller
authors.affiliation: Faculty of Biology, Microbiology, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Grohmann
mesh_terms: D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D006094:Gram-Positive Bacteria / Q000235:genetics* / Q000502:physiology; D046911:Macromolecular Substances / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009876:Operon; D000069319:Type IV Secretion Systems / Q000235:genetics / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; D000069319:Type IV Secretion Systems