Single-Molecule Insights into ATP-Dependent Conformational Dynamics of Nucleoprotein Filaments of <i>Deinococcus radiodurans</i> RecA

• Main Authors: Aleksandr Alekseev, Galina Cherevatenko, Maksim Serdakov, Georgii Pobegalov, Alexander Yakimov, Irina Bakhlanova, Dmitry Baitin, Mikhail Khodorkovskii
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: International Journal of Molecular Sciences
• Subjects: homologous recombination; DNA repair; RecA; <i>Deinococcus radiodurans</i>
• Online Access: https://www.mdpi.com/1422-0067/21/19/7389

<i>Deinococcus radiodurans</i> (Dr) has one of the most robust DNA repair systems, which is capable of withstanding extreme doses of ionizing radiation and other sources of DNA damage. DrRecA, a central enzyme of recombinational DNA repair, is essential for extreme radioresistance. In the presence of ATP, DrRecA forms nucleoprotein filaments on DNA, similar to other bacterial RecA and eukaryotic DNA strand exchange proteins. However, DrRecA catalyzes DNA strand exchange in a unique reverse pathway. Here, we study the dynamics of DrRecA filaments formed on individual molecules of duplex and single-stranded DNA, and we follow conformational transitions triggered by ATP hydrolysis. Our results reveal that ATP hydrolysis promotes rapid DrRecA dissociation from duplex DNA, whereas on single-stranded DNA, DrRecA filaments interconvert between stretched and compressed conformations, which is a behavior shared by <i>E. coli</i> RecA and human Rad51. This indicates a high conservation of conformational switching in nucleoprotein filaments and suggests that additional factors might contribute to an inverse pathway of DrRecA strand exchange.