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You are here: Home / Teams / Posttranscriptional Regulation in Infection and Oncogenesis - Jalinot/Mocquet / Publications / Structural mechanism underpinning Thermus oshimai Pif1-mediated G-quadruplex unfolding.

Structural mechanism underpinning Thermus oshimai Pif1-mediated G-quadruplex unfolding.

Yang-Xue Dai, Hai-Lei Guo, Na-Nv Liu, Wei-Fei Chen, Xia Ai, Hai-Hong Li, Bo Sun, Xi-Miao Hou, Stephane Rety, and Xu-Guang Xi (2022)

EMBO Rep:e53874.

G-quadruplexes (G4s) are unusual stable DNA structures that cause genomicinstability. To overcome the potential barriers formed by G4s, cells have evolveddifferent families of proteins that unfold G4s. Pif1 is a DNA helicase fromsuperfamily 1 (SF1) conserved from bacteria to humans with high G4-unwindingactivity. Here, we present the first X-ray crystal structure of the Thermusoshimai Pif1 (ToPif1) complexed with a G4. Our structure reveals that ToPif1recognizes the entire native G4 via a cluster of amino acids at domains 1B/2Bwhich constitute a G4-Recognizing Surface (GRS). The overall structure of the G4maintains its three-layered propeller-type G4 topology, without significantreorganization of G-tetrads upon protein binding. The three G-tetrads in G4 arerecognized by GRS residues mainly through electrostatic, ionic interactions, andhydrogen bonds formed between the GRS residues and the ribose-phosphate backbone.Compared with previously solved structures of SF2 helicases in complex with G4,our structure reveals how helicases from distinct superfamilies adopt differentstrategies for recognizing and unfolding G4s.

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