Helicase

A motor enzyme that uses energy, usually from ATP, to separate paired DNA or RNA strands. Helicases move along nucleic acids and disrupt base pairing, enabling processes such as replication and repair.

ATP hydrolysis: The chemical reaction that breaks ATP into ADP and inorganic phosphate, releasing free energy. Many helicases couple this reaction to movement and strand separation.
DNA: A usually double-stranded nucleic acid that stores hereditary information in cells. DNA is the principal substrate for helicases in replication and genome maintenance.
DNA replication: The cellular process of copying DNA before cell division. Replication forks require helicase activity to expose templates for DNA synthesis.
Topoisomerase: An enzyme that changes DNA topology by transiently breaking and rejoining DNA strands. Topoisomerases relieve torsional stress created ahead of unwinding helicases.
DnaB helicase: The bacterial replicative helicase that unwinds DNA at the replication fork. DnaB is a canonical ring-shaped helicase that encircles one DNA strand.
Nucleic acid secondary structure: The local folding of DNA or RNA strands through base pairing and other molecular interactions. Helicases resolve paired structures formed within or between nucleic-acid strands.
RNA: A nucleic acid involved in gene expression, regulation, and other cellular functions. RNA helicases remodel RNA structures and RNA–protein complexes.
DNA repair: Cellular processes that detect and correct damage or errors in DNA. Repair pathways use helicases to open DNA around lesions and processing sites.
RNA polymerase: An enzyme that synthesizes RNA using a nucleic-acid template. Polymerases copy exposed templates; helicases separate strands without synthesizing a complementary chain.
MCM complex: A six-subunit eukaryotic helicase complex that unwinds DNA during replication. MCM illustrates how eukaryotes organize helicase activity within the replisome.

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