PIF1
Description
The PIF1 (PIF1 5'-to-3' DNA helicase) is a protein-coding gene located on chromosome 15.
Helicases are enzymes crucial for all organisms, primarily responsible for unpacking genetic material. They act as motor proteins, moving along nucleic acid strands to separate hybridized strands using energy from ATP hydrolysis. The variety of helicases reflects the diverse processes requiring strand separation. Approximately 1% of eukaryotic genes encode helicases. The human genome harbors 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases. Many cellular processes, including DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis, involve separating nucleic acid strands, necessitating the use of helicases. Certain specialized helicases play a role in sensing viral nucleic acids during infection, contributing to immune function. A helicase is an enzyme vital for DNA replication and repair, unwinding the double-stranded DNA molecule by breaking hydrogen bonds between base pairs, enabling strand separation.
PIF1 is a DNA-dependent ATPase and 5'-3' DNA helicase that is essential for maintaining the stability of both the mitochondrial and nuclear genomes. It efficiently unwinds G-quadruplex (G4) DNA structures and forked RNA-DNA hybrids. PIF1 resolves G4 structures, preventing replication pausing and double-strand breaks (DSBs) at G4 motifs. It also plays a role in maintaining telomeric DNA. PIF1 inhibits telomere elongation, de novo telomere formation, and telomere addition to DSBs through catalytic inhibition of telomerase. It reduces the processivity of telomerase by displacing active telomerase from DNA ends. PIF1 releases telomerase by unwinding the short telomerase RNA/telomeric DNA hybrid, which is an intermediate in the telomerase reaction. PIF1 possesses an intrinsic strand annealing activity.
PIF1 is also known as C15orf20, PIF.
