title: Unconventional lateral gene transfer in extreme thermophilic bacteria.
abstract: Conjugation and natural competence are two major mechanisms that explain the acquisition of foreign genes throughout bacterial evolution. In recent decades, several studies in model organisms have revealed in great detail the steps involved in such processes. The findings support the idea that the major basis of these mechanisms is essentially similar in all bacteria. However, recent work has pinpointed the existence of new, evolutionarily different processes underlying lateral gene transfer. In Thermus thermophilus HB27, at least 16 proteins are required for the activity of one of the most efficient natural competence systems known so far. Many of those proteins have no similarities to proteins involved in natural competence in other well-known models. This unusual competence system is conserved, in association with the chromosome, in all other Thermus spp. genomes so far available, it being functional even in strains from isolated environments, such as deep mines. Conjugation is also possible among Thermus spp. Homologues to proteins implicated in conjugation in model bacteria are encoded in the genome of a recently sequenced strain of Thermus thermophilus and shared by other members of the genus. Nevertheless, processive DNA transfer in the absence of a functional natural competence system in strains in which no conjugation homologous genes can be found hints at the existence of an additional and unconventional conjugation mechanism in these bacteria.
authors.affiliation: Center for Molecular Biology Severo Ochoa, Autonomous University of Madrid-CSIC, Cantoblanco, Madrid, Spain.
authors.forename: Carolina E
authors.initials: CE
authors.lastname: César
authors.forename: Laura
authors.initials: L
authors.lastname: Álvarez
authors.forename: Carlos
authors.initials: C
authors.lastname: Bricio
authors.forename: Esta
authors.initials: E
authors.lastname: van Heerden
authors.forename: Dereck
authors.initials: D
authors.lastname: Littauer
authors.forename: José
authors.initials: J
authors.lastname: Berenguer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003227:Conjugation, Genetic; D017124:Conserved Sequence; D061269:DNA Transformation Competence; D022761:Gene Transfer, Horizontal; D013824:Thermus / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins