Structural mechanisms of DNA binding and unwinding in bacterial RecQ helicases

摘要: RecQ helicases unwind remarkably diverse DNA structures as key components of many cellular processes. How enzymes accommodate different substrates in a unified mechanism that couples ATP hydrolysis to unwinding is unknown. Here, the X-ray crystal structure Cronobacter sakazakii catalytic core domain bound duplex with 3′ single-stranded extension identifies two DNA-dependent conformational rearrangements: winged-helix pivots ∼90° close onto DNA, and conserved aromatic-rich loop remodeled bind ssDNA. These changes coincide restructuring ATPase active site positions residues for hydrolysis. Complex formation also induces tight bend melts portion duplex. This bending, coupled translocation, could provide other structures.