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Structural mechanisms of DNA binding and unwinding in bacterial RecQ helicases.

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

SUBMITTER: Manthei KA

PROVIDER: S-EPMC4394303 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Structural mechanisms of DNA binding and unwinding in bacterial RecQ helicases.

Manthei Kelly A KA Hill Morgan C MC Burke Jordan E JE Butcher Samuel E SE Keck James L JL

Proceedings of the National Academy of Sciences of the United States of America 20150323 14

RecQ helicases unwind remarkably diverse DNA structures as key components of many cellular processes. How RecQ enzymes accommodate different substrates in a unified mechanism that couples ATP hydrolysis to DNA unwinding is unknown. Here, the X-ray crystal structure of the Cronobacter sakazakii RecQ catalytic core domain bound to duplex DNA with a 3' single-stranded extension identifies two DNA-dependent conformational rearrangements: a winged-helix domain pivots ∼90° to close onto duplex DNA, an ...[more]

PMID: 25831501

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