Identification and characterization of repetitive extragenic palindromes (REP)-associated tyrosine transposases: implications for REP evolution and dynamics in bacterial genomes
Abstract
Bacterial repetitive extragenic palindromes (REPs) compose a distinct group of genomic repeats. They occur in high abundance (>100 copies/genome) and are often arranged in mosaic elements (BIMEs).
In BIMEs, regularly spaced REPs are present in alternating orientations. BIMEs and REPs play role in chromosome organization and transcription termination.
Their origins are, unknown. In this report, we describe a novel class of putative transposases related to IS200/IS605 transposase family and we demonstrate that they are obligately associated with bacterial REPs.
Open reading frames coding these tyrosine transposases (RAYTs) are always flanked by two REPs in inverted orientation and thus constitute typical transposable elements. RAYTs and their flanking REPs apparently coevolve with each other.
We propose that RAYTs are responsible for establishment of REPs and BIMEs in bacterial genomes. We suggest that BIMEs are a special type of nonautonomous transposable elements, mobilizable by RAYTs.