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ICEA of M ycoplasma agalactiae : a new family of self‐transmissible integrative elements that confers conjugative properties to the recipient strain
Author(s) -
Dordet Frisoni Emilie,
Marenda Marc Serge,
Sagné Eveline,
Nouvel Laurent Xavier,
Guérillot Romain,
Glaser Philippe,
Blanchard Alain,
Tardy Florence,
SirandPugnet Pascal,
Baranowski Eric,
Citti Christine
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12341
Subject(s) - biology , extrachromosomal dna , transposase , genetics , horizontal gene transfer , genome , plasmid , in silico , gene , transposable element , mutant , mycoplasma , pathogenicity island , bacterial genetics , microbiology and biotechnology , escherichia coli
Summary Horizontal gene transfer ( HGT ) is a major force of microbial evolution but was long thought to be marginal in mycoplasmas. In silico detection of exchanged regions and of loci encoding putative Integrative Conjugative Elements ( ICE ) in several mycoplasma genomes challenged this view, raising the prospect of these simple bacteria being able to conjugate. Using the model pathogen M ycoplasma agalactiae , we demonstrated for the first time that one of these elements, ICEA , is indeed self‐transmissible. As a hallmark of conjugative processes, ICEA transfers were DNase resistant and required viable cells. ICEA acquisition conferred ICE ‐negative strains with the new ability to conjugate, allowing the spread of ICEA . Analysis of transfer‐deficient mutants indicated that this process requires an ICEA ‐encoded lipoprotein of unknown function, CDS 14. Formation of a circular extrachromosomal intermediate and the subsequent chromosomal integration of ICEA involved CDS 22, an ICEA ‐encoded product distantly related to the ISLre 2 transposase family. Remarkably, ICEA has no specific or no preferential integration site, often resulting in gene disruptions. Occurrence of functional mycoplasma ICE offers these bacteria with a means for HGT , a phenomenon with far‐reaching implications given their minute‐size genome and the number of species that are pathogenic for a broad host‐range.