Power of Microbes in Industry and Environment 2023

Genome stability is of paramount importance to all living organisms. Genome instability results in severe conditions such as cancer and premature aging in mammals, due to aberrant DNA rearrangements such as deletions, amplifications, translocations etc. Stability of Escherichia coli genome is determined by metabolism of 3 ́-ending tails at DNA double-strand breaks, which are faithfully mended by homologous recombination catalyzed by RecBCD enzyme in wild-type (wt) cells. However, occasionally aberrant DNA transactions occur in E. coli genome, which are mediated by microhomologies and result in illegitimate recombination (IR) events. The main genome caretaker in bacteria and eukaryotes is RecQ-class of proteins, which disrupt the aberrant DNA structures. The  Spi- assay is used to quantify the frequency of IR in E. coli genome. It detects aberrantly excised λ prophage that contains part of bacterial genome while lacking part of its own genome (Fig. 1). Such phages can grow on P2 lysogenic bacteria, unlike wt phages. Bacterial SSB proteins, as well as their eukaryotic RPA analogues, are essential and ubiquitous. They avidly bind single- stranded DNA and regulate/coordinate its metabolism, hence enabling essential DNA processes such as replication and repair. Here we assessed the effect of SSB protein on IR occurrence in E. coli genome.