Structural and Functional Characterization of an SMC-like Protein RecN: New Insights into Double-Strand Break Repair

• Published in: Structure (London) Vol. 20; no. 12; pp. 2076 - 2089
• Main Authors: Pellegrino, Simone, Radzimanowski, Jens, de Sanctis, Daniele, Erba, Elisabetta Boeri, McSweeney, Sean, Timmins, Joanna
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 05.12.2012
• Subjects: Adenosine Triphosphate - chemistry; Amino Acid Sequence; Amino Acid Substitution; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Binding Sites; Crystallography, X-Ray; Deinococcus; Deinococcus radiodurans; DNA Breaks, Double-Stranded; DNA Repair; DNA Restriction Enzymes - chemistry; DNA Restriction Enzymes - genetics; Hydrogen Bonding; Hydrolysis; Kinetics; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Protein Binding; Protein Interaction Domains and Motifs; Protein Structure, Quaternary; Protein Structure, Secondary; Scattering, Small Angle
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2012.09.010

Repair of DNA double-strand breaks (DSBs) is essential for cell survival and maintaining genome integrity. DSBs are repaired in a stepwise manner by homologous recombination. Here, we focused on the early steps of DSB repair, including DSB recognition, which is still only poorly understood. In prokaryotes, this process has been proposed to involve the RecN protein, a member of the structural maintenance of chromosome (SMC) protein family, which include key eukaryotic and prokaryotic proteins such as cohesin, condensin, and Rad50. An extensive high- and low-resolution structural analysis of Deinococcus radiodurans RecN using a combination of protein crystallography and small-angle X-ray scattering enabled us to assemble a quasi-atomic model of the entire RecN protein, representing the complete structure of a SMC-like protein. These results, together with a thorough biochemical and mutational study of RecN, allow us to propose a model for the role of RecN in DSB repair. ► Our data provide a quasi-atomic model of the entire RecN protein ► This structure represents the full structure of a SMC-like protein ► RecN is a very elongated (300 Å long) and rigid dimeric assembly ► The ATPase and DNA binding activities of RecN reside in its head domains DNA double-strand breaks (DSB) are a serious threat to genome stability and cell survival. DSBs are repaired in a stepwise manner by homologous recombination. Pellegrino et al. focus on the early steps of DSB repair and present a structure and a model of the entire RecN protein, the first for an SMC-like protein.