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Stimulation of ATP Hydrolysis by ssDNA Provides the Necessary Mechanochemical Energy for G4 Unfolding.
J Mol Biol, 436(2):168373.
The G-quadruplex (G4) is a distinct geometric and electrophysical structurecompared to classical double-stranded DNA, and its stability can impede essentialcellular processes such as replication, transcription, and translation. Thisstudy focuses on the BsPif1 helicase, revealing its ability to bind independentlyto both single-stranded DNA (ssDNA) and G4 structures. The unfolding activity ofBsPif1 on G4 relies on the presence of a single tail chain, and the covalentcontinuity between the single tail chain and the G4's main chain is necessary forefficient G4 unwinding. This suggests that ATP hydrolysis-driven ssDNAtranslocation exerts a pull force on G4 unwinding. Molecular dynamics simulationsidentified a specific region within BsPif1 that contains five crucial amino acidsites responsible for G4 binding and unwinding. A "molecular wire stripper" modelis proposed to explain BsPif1's mechanism of G4 unwinding. These findings providea new theoretical foundation for further exploration of the G4 developmentmechanism in Pif1 family helicases.
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