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DnaB helicase is an enzyme in bacteria which opens the replication fork during DNA replication.Although the mechanism by which DnaB both couples ATP hydrolysis to translocation along DNA and denatures the duplex is unknown, a change in the quaternary structure of the protein involving dimerisation of the N-terminal domain has been observed and may occur during the enzymatic cycle. [1]
DNA helicases are frequently attracted to regions of DNA damage and are essential for cellular DNA replication, recombination, repair, and transcription. Chemical manipulation of their molecular processes can change the rate at which cancer cells divide, as well as, the efficiency of transactions and cellular homeostasis.
The process of semiconservative replication for the site of DNA replication is a fork-like DNA structure, the replication fork, where the DNA helix is open, or unwound, exposing unpaired DNA nucleotides for recognition and base pairing for the incorporation of free nucleotides into double-stranded DNA. [3]
Eukaryotes initiate DNA replication at multiple points in the chromosome, so replication forks meet and terminate at many points in the chromosome. Because eukaryotes have linear chromosomes, DNA replication is unable to reach the very end of the chromosomes. Due to this problem, DNA is lost in each replication cycle from the end of the chromosome.
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 ...
RecQ helicase is a family of helicase enzymes initially found in Escherichia coli [1] that has been shown to be important in genome maintenance. [2] [3] [4] They function through catalyzing the reaction ATP + H 2 O → ADP + P and thus driving the unwinding of paired DNA and translocating in the 3' to 5' direction.
DNA replication. The two base-pair complementary chains of the DNA molecule allow replication of the genetic instructions. The "specific pairing" is a key feature of the Watson and Crick model of DNA, the pairing of nucleotide subunits. [5] In DNA, the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. The A:T ...
Stalled replication forks often lead to DNA breakage, further implicating the importance of unimpaired replication forks on genome integrity. [6] RRM3 helps cells progress through stalled replication forks, although this is a mechanism that is still poorly understood. [6] Rrm3p is one of many helicase proteins in Saccharomyces cerevisiae. Rrm3p ...