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It participates in transcription, the cell cycle, and DNA repair. According to recent research, missense mutations in the RECQ1 gene may play a role in the development of familial breast cancer. DNA helicases are frequently attracted to regions of DNA damage and are essential for cellular DNA replication, recombination, repair, and transcription.
The structure of the helicase has been solved at high resolution and indicates "inchworming" as the mechanism of translocation on single-stranded DNA. A Mexican-wave model has been proposed based on the changes in conformation of the helicase observed in the product versus substrate complex.
For DNA polymerases to function, the double-stranded DNA helix has to be unwound to expose two single-stranded DNA templates for replication. DNA helicases are responsible for unwinding the double-stranded DNA during chromosome replication. Helicases in eukaryotic cells are remarkably complex. [106]
The replication fork is a structure that forms within the long helical DNA during DNA replication. It is produced by enzymes called helicases that break the hydrogen bonds that hold the DNA strands together in a helix.
DNA is a duplex formed by two anti-parallel strands. Following Meselson-Stahl, the process of DNA replication is semi-conservative, whereby during replication the original DNA duplex is separated into two daughter strands (referred to as the leading and lagging strand templates). Each daughter strand becomes part of a new DNA duplex.
The minichromosome maintenance protein complex (MCM) is a DNA helicase essential for genomic DNA replication. Eukaryotic MCM consists of six gene products, Mcm2–7, which form a heterohexamer. Eukaryotic MCM consists of six gene products, Mcm2–7, which form a heterohexamer.
Helicase, POLQ-like, also known as Helicase Q (HELQ), HEL308 and Holliday junction migration protein, encoded by the gene HELQ1, is a DNA helicase found in humans, archea and many other organisms. [5] HelQ is a replication-linked repair helicase that preserves DNA integrity through helping in the repair of DNA that has become damaged. [6]
The crystal structure of the Ter DNA-Tus protein complex (A) showing the nonblocking and the fork-blocking faces of Tus. (B) A cross-sectional view of the helicase-arresting surface. Replication of the DNA separating the opposing replication forks leaves the completed chromosomes joined as ‘catenanes’ or topologically interlinked circles ...