Domain structure and dynamics in the helical filaments formed by RecA and Rad51 on DNA

Two distinct conformational states define the interaction of human RAD 51‐ ATP with single‐stranded DNA

“…On the basis of electron microscopy experiments, it has been proposed that hRAD51‐ssDNA NPFs are characterized by a high degree of conformational freedom (Yu et al , 2001). This is in line with our results from both single‐molecule and crystallography analyses, showing the occurrence of different hRAD51‐ssDNA filament states.…”

“…One well‐established feature of the NPF structure is its remarkable conservation across the kingdoms of life, which is accompanied by considerable conformational polymorphism, resulting from variations in helical rise and twist (Ogawa et al , 1993; Yu  et al , 2001; Liu et al , 2004). Such heterogeneity, captured by structural analysis, is likely to reflect the NPF ability to undergo conformational transitions that alter its pitch, giving rise to extended or compact filament states.…”

“…Electron microscopy data have shown that the nature of the nucleotide bound to RAD51 has a marked effect on filament conformation: NPFs containing the structural analogue of the ATP transition state ADP·AlF4 − adopt an extended conformation with a pitch of 9.9 nm, while ATPγS‐bound NPFs adopt a more compact conformation with a pitch of ~7.6 nm (Yu et al , 2001). More recently, high‐resolution cryo‐electron microscopy (cryoEM) studies of the presynaptic NPF in the presence of the ATP analogue AMP‐PNP have measured an average filament pitch of 10.3 nm with 6.4 protomers per turn (Short et al , 2016) and confirmed its structural polymorphism, with 80% of the filaments having pitch values in the range of 9.5–11.0 nm; a similar cryoEM analysis of the active form of the NPF reported a filament pitch of 10.0 nm with 6.3 protomers per turn (Xu et al , 2017).…”

“…Thus, ATP hydrolysis affects the behaviour of the hRAD51 NPF, as a dynamic entity that is able to switch between multiple conformations (Yu et al , 2001). Although large‐scale differences in NPF structure, such as variations in pitch, have been widely reported, local changes in filament structure at the single protomer level have not been described yet.…”

DNA-Pairing and Annealing Processes in Homologous Recombination and Homology-Directed Repair

“…Presynaptic filament assembly activates the catalytic activities of the DNA-pairing protein, including ATP hydrolysis, plus ATP-dependent pairing and strand exchange reactions with a homologous duplex. The binding and hydro- lysis of ATP modulates the structure of presynaptic filaments between ATP-bound "active" and ADP-bound or nucleotide-free "inactive" conformations: The active filament has a high helical pitch in which the bound DNA is significantly stretched (helical pitch of 95 -99 Å , depending on species), whereas the inactive filament has a low helical pitch (70 -76 Å , depending on species) (Griffith and Formosa 1985;Egelman 1992, 1993;Ogawa et al 1993;Yang et al 2001;Yu et al 2001). These and other factors influencing the dynamics of presynaptic filaments are the subject of a recent review (Liu et al 2011a).…”