title: The tetracycline resistance gene tet(M) exhibits mosaic structure.
abstract: Tetracycline resistance genes of the M class, tet(M), are typically found on mobile genetic elements as the conjugative transposons of gram-positive bacteria. By comparing the sequences of eight different tet(M) genes (from Enterococcus faecalis, Streptococcus pneumoniae, Staphylococcus aureus, Ureaplasma urealyticum, and Neisseria), a mosaic structure was detected which could be traced to two distinct alleles. The two alleles displayed a divergence of 8% and a different G/C content. The block structure of these genes provides evidence for the contribution of homologous recombination to the evolution and the heterogeneity of the tet(M) locus. Unlike described cases of chromosomally located mosaic loci, tet(M) is a relatively recently acquired determinant in the species examined and it would appear that mosaic structure within tet(M) has evolved after acquisition of the gene by the mobile genetic elements upon which it is located.
authors.affiliation: Dipartimento di Biologia Molecolare, Università di Siena, Italy. oggioni@unisi.it
authors.forename: M R
authors.initials: MR
authors.lastname: Oggioni
authors.forename: C G
authors.initials: CG
authors.lastname: Dowson
authors.forename: J M
authors.initials: JM
authors.lastname: Smith
authors.forename: R
authors.initials: R
authors.lastname: Provvedi
authors.forename: G
authors.initials: G
authors.lastname: Pozzi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004269:DNA, Bacterial; D013293:Enterococcus faecalis / Q000235:genetics; D008969:Molecular Sequence Data; D009030:Mosaicism / Q000235:genetics*; D009344:Neisseria gonorrhoeae / Q000235:genetics; D009345:Neisseria meningitidis / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013211:Staphylococcus aureus / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000235:genetics; D013753:Tetracycline Resistance / Q000235:genetics*; D016990:Ureaplasma urealyticum / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C083138:Tet M resistance protein, Bacteria