Helicase

Helicases are a class of enzymes thought to be vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleotidic backbone, separating two hybridized nucleic acid strands (hence helic- + -ase), using energy from ATP hydrolysis. There are many helicases, representing the great variety of processes in which strand separation must be catalyzed. Approximately 1% of eukaryotic genes code for helicases.^[1]

The human genome codes for 95 non-redundant helicases: 64 RNA helicases and 31 DNA helicases.^[2] Many cellular processes, such as DNA replication, transcription, translation, recombination, DNA repair, and ribosome biogenesis involve the separation of nucleic acid strands that necessitates the use of helicases. Some specialized helicases are also involved in sensing of viral nucleic acids during infection and fulfill an immunological function. A helicase is an enzyme that plays a crucial role in the DNA replication and repair processes. Its primary function is to unwind the double-stranded DNA molecule by breaking the hydrogen bonds between the complementary base pairs, allowing the DNA strands to separate. This creates a replication fork, which serves as a template for synthesizing new DNA strands. Helicase is an essential component of cellular mechanisms that ensures accurate DNA replication and maintenance of genetic information. DNA helicase catalyzes regression. RecG and the enzyme PriA work together to rewind duplex DNA, creating a Holliday junction. RecG releases bound proteins and the PriA helicase facilitates DNA reloading to resume DNA replication. RecG replaces the single-strand binding protein (SSB), which regulates the helicase-fork loading sites during fork regression. The SSB protein interacts with DNA helicases PriA and RecG to recover stalled DNA replication forks. These enzymes must bind to the SSB-helicase to be loaded onto stalled forks. Thermal sliding and DNA duplex binding are possibly supported by the wedge domain of RecG's association with the SSB linker. In a regression reaction facilitated by RecG and ATPHollidayjunctions are created for later processing.