Evidence for past integration of IncP-1 plasmids into bacterial chromosomes.
Plasmids of the IncP-1 incompatibility group are self-transmissible between and stably maintained in a very broad range of Gram-negative bacteria. A characteristic feature of IncP-1 genomes is the existence of multiple binding sites (OB) for the KorB protein which plays a dual role in active partitioning of plasmid and coordinate regulation of expression of genes for replication, maintenance and transfer. A search of the available bacterial genome sequences revealed a significant number (70 out of 322) with one or more putative KorB binding sites. Binding of KorB to such a site was demonstrated by chromatin immunoprecipitation (ChIP) for Pseudomonas putida KT2440. While such a site may arise by chance, this is unlikely for Pseudomonas aeruginosa UCBPP-PA14 whose genome sequence contains four clustered OB sites and several regions have more than 80% nucleotide identity to traJ, trbJ and trbL of IncP-1 plasmids. A number of other bacterial genomes also contain integrated partial IncP-1 genomes or their remnants. These data provide evidence for multiple past integration events of IncP-1 plasmids into bacterial chromosomes and provide new evidence for IncP-1 plasmids being important elements in gene mobility.
Chiu
Chung-Min
CM
School of Bioscience, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Thomas
Christopher M
CM
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D047369:Chromatin Immunoprecipitation; D002876:Chromosomes, Bacterial / Q000235:genetics*; D003227:Conjugation, Genetic; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D006090:Gram-Negative Bacteria / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*
D001426:Bacterial Proteins; C053863:KorB protein, Plasmid RK2