title: Translocation of Saccharomyces cerevisiae Pif1 helicase monomers on single-stranded DNA.
abstract: In Saccharomyces cerevisiae Pif1 participates in a wide variety of DNA metabolic pathways both in the nucleus and in mitochondria. The ability of Pif1 to hydrolyse ATP and catalyse unwinding of duplex nucleic acid is proposed to be at the core of its functions. We recently showed that upon binding to DNA Pif1 dimerizes and we proposed that a dimer of Pif1 might be the species poised to catalysed DNA unwinding. In this work we show that monomers of Pif1 are able to translocate on single-stranded DNA with 5' to 3' directionality. We provide evidence that the translocation activity of Pif1 could be used in activities other than unwinding, possibly to displace proteins from ssDNA. Moreover, we show that monomers of Pif1 retain some unwinding activity although a dimer is clearly a better helicase, suggesting that regulation of the oligomeric state of Pif1 could play a role in its functioning as a helicase or a translocase. Finally, although we show that Pif1 can translocate on ssDNA, the translocation profiles suggest the presence on ssDNA of two populations of Pif1, both able to translocate with 5' to 3' directionality.
authors: 252 McDonnell Science Building, Department of Biochemistry and Molecular Biophysics, Washington University, School of Medicine, 660 South Euclid Avenue, MS8231, Saint Louis, MO 63110, USA.galletto@biochem.wustl.edu
authors: Roberto
authors: R
authors: Galletto
authors: Eric J
authors: EJ
authors: Tomko
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D008954:Models, Biological; D055503:Protein Multimerization; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; C085463:PIF1 protein, S cerevisiae; D004265:DNA Helicases