PIF1

PIF1 is a DNA-dependent adenosine triphosphate (ATP)-metabolizing enzyme that functions as a 5' to 3' DNA helicase. The encoded protein can resolve G-quadruplex structures and RNA-DNA hybrids at the ends of chromosomes. It also prevents telomere elongation by inhibiting the actions of telomerase. Alternative splicing and the use of alternative start codons results in multiple isoforms that are differentially localized to either the mitochondria or the nucleus.

Full Name

PIF1 5'-To-3' DNA Helicase

Function

DNA-dependent ATPase and 5'-3' DNA helicase required for the maintenance of both mitochondrial and nuclear genome stability. Efficiently unwinds G-quadruplex (G4) DNA structures and forked RNA-DNA hybrids. Resolves G4 structures, preventing replication pausing and double-strand breaks (DSBs) at G4 motifs. Involved in the maintenance of telomeric DNA. Inhibits telomere elongation, de novo telomere formation and telomere addition to DSBs via catalytic inhibition of telomerase. Reduces the processivity of telomerase by displacing active telomerase from DNA ends. Releases telomerase by unwinding the short telomerase RNA/telomeric DNA hybrid that is the intermediate in the telomerase reaction. Possesses an intrinsic strand annealing activity.

Biological Process

DNA duplex unwindingManual Assertion Based On ExperimentIBA:GO_Central
DNA recombinationIEA:UniProtKB-UniRule
DNA repairIEA:UniProtKB-UniRule
DNA replicationManual Assertion Based On ExperimentIBA:GO_Central
Mitochondrial genome maintenanceIEA:UniProtKB-UniRule
Negative regulation of telomerase activityManual Assertion Based On ExperimentIDA:HGNC-UCL
Negative regulation of telomere maintenance via telomeraseManual Assertion Based On ExperimentIDA:BHF-UCL
Regulation of telomere maintenanceManual Assertion Based On ExperimentIDA:HGNC-UCL
Telomere maintenance via telomeraseTAS:Reactome

Cellular Location

Nucleus
Isoform 4
Mitochondrion