Genetics of recombination in the model bacterium escherichia coli

Homologous recombination in bacteria was originally discovered as a process that not only exchanges genetic material but also provides one of the major pathways of DNA-damage repair. Homologous exchanges and DNA repair illustrate the dual role of recombination which acts both to promote genetic diversity and to conserve genomic integrity. In this review, we will first describe the genetics of enzymes that act at different steps of the homologous recombination process in Escherichia coli, with an emphasis on the most recent results. We will then describe recent advances in our understanding of the role of homologous recombination during DNA repair. Recombination enzymes act on DNA at single- or double-strand interruptions generated as a result of nucleotide lesions or replication impairment. Although generally they can and often do promote genetic exchange, some recombination enzymes also fulfill various non-recombinogenic important functions, such as the signaling of DNA damage and the remodeling of arrested replication forks.