Pif1 is a DNA helicase conserved from bacteria to humans. It suppresses both G-quadruplex-associated DNA damage and telomere lengthening. In budding yeast, it exists in two forms, nuclear and mitochondrial forms. Its nuclear form inhibits telomerase, while its mitochondrial is involved in repair and recombination of mitochondrial DNA. These proteins belong to the helicase superfamily 1 (SF1) and contain RecA-like domains (1A and 2A) which, together with two additional domains, 1B and 2B, form the helicase core [1,2]. This entry represents domain 2B, which adopts a SH3-like fold.

1: Structural and functional analysis of the nucleotide and DNA binding activities of the human PIF1 helicase. Dehghani-Tafti S, Levdikov V, Antson AA, Bax B, Sanders CM; Nucleic Acids Res. 2019;47:3208-3222. PMID:30698796

2: Insights into the structural and mechanistic basis of multifunctional S. cerevisiae Pif1p helicase. Lu KY, Chen WF, Rety S, Liu NN, Wu WQ, Dai YX, Li D, Ma HY, Dou SX, Xi XG; Nucleic Acids Res. 2018;46:1486-1500. PMID:29202194