Bacterial interspersed mosaic elements (BIMEs) are a major source of sequence polymorphism in Escherichia coli intergenic regions including specific associations with a new insertion sequence.
A significant fraction of Escherichia coli intergenic DNA sequences is composed of two families of repeated bacterial interspersed mosaic elements (BIME-1 and BIME-2). In this study, we determined the sequence organization of six intergenic regions in 51 E. coli and Shigella natural isolates. Each region contains a BIME in E. coli K-12. We found that multiple sequence variations are located within or near these BIMEs in the different bacteria. Events included excisions of a whole BIME-1, expansion/deletion within a BIME-2 and insertions of non-BIME sequences like the boxC repeat or a new IS element, named IS 1397. Remarkably, 14 out of IS 1397 integration sites correspond to a BIME sequence, strongly suggesting that this IS element is specifically associated with BIMEs, and thus inserts only in extragenic regions. Unlike BIMEs, IS 1397 is not detected in all E. coli isolates. Possible relationships between the presence of this IS element and the evolution of BIMEs are discussed.
Bachellier
S
S
Unité de Programmation Moléculaire et Toxicologie Génétique, CNRS URA 1444, Institut Pasteur, Paris, France.
Clément
J M
JM
Hofnung
M
M
Gilson
E
E
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009030:Mosaicism; D011110:Polymorphism, Genetic; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012763:Shigella flexneri / Q000235:genetics; D012764:Shigella sonnei / Q000235:genetics
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C085896:OrfB protein, E coli