Interactions of the Escherichia coli SMC-like RecN protein with different forms of DNA revealed at the single-molecule level using optical tweezers

DNA molecule is the storage of genetic information in all living organisms. Its integrity is critical to life. However, due to the exposure to various environmental factors and endogenous agents, double-strand DNA breaks occur. Bacteria are capable to restore their genome integrity through a process called the SOS response. The key protein of SOS response is the RecA recombinase. Also critical for DNA repair is the SMC-like RecN protein, which helps RecA to find the homologous DNA template. Currently, its functions and mechanism of action remain poorly understood. In this work, using optical tweezers, we show predominant binding of RecN to ssDNA and also demonstrate a weak binding of dsDNA causing a condition similar to DNA loops formation.