dnaC is a loading factor that complexes with the C-terminus of
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 nucleic acid phosphodiester backbone, separatin ...
dnaB and inhibits it from unwinding the dsDNA at a replication fork.
A dnaB and dnaC associate near the
dnaA
Introduction
Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. DnaA is a protein that activates initiation of DNA replica ...
bound origin for each of the ssDNA.
One dnaB-dnaC complex is oriented in the opposite direction to the other dnaB-dnaC complex due to the antiparallel nature of DNA. Because they are oriented in opposite directions, one dnaB-dnaC complex will complex with dnaA from the
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
of dnaB whereas the other dnaB-dnaC complex will complex with dnaA from the dnaC. After the assembly of dnaG onto the N-terminus of dnaB, dnaC is released and dnaB will be allowed to begin unwinding dsDNA to make room for
DNA polymerase III
DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNA replication. It was discovered by Thomas Kornberg (son of Arthur Kornberg) and Malcolm Gefter in 1970. The complex has high processivity (i.e. the number of ...
to begin synthesizing the daughter strands.
This interaction of dnaC with dnaB requires the hydrolysis of
ATP.
References
External links
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{{DNA replication
Bacterial proteins
DNA replication