Related Experiment Video
Updated: Aug 1, 2026
07:18
Visualization of DNA Replication in the Vertebrate Model System DT40 using the DNA Fiber Technique
Published on: October 27, 2011
Preventing re-replication of DNA in a single cell cycle: evidence for a replication licensing factor
1ICRF Clare Hall Laboratories, Potters Bar, Herts, England.
The Journal of Cell Biology
|September 1, 1993
Summary
A novel replication factor, essential for initiating DNA replication, is discovered. This factor modifies chromatin in early G1, ensuring eukaryotic DNA replicates only once per cell cycle.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Eukaryotic DNA replication is tightly regulated to occur once per cell cycle.
- The precise mechanisms ensuring mono-replication remain incompletely understood.
- Previous models proposed a Replication Licensing Factor (RLF) but lacked direct evidence.
Purpose of the Study:
- To identify and characterize the factor responsible for limiting DNA replication to a single round per cell cycle.
- To elucidate the mechanism by which this factor regulates DNA replication initiation.
- To understand the cell cycle-dependent regulation of this crucial replication control element.
Main Methods:
- Utilizing Xenopus egg extracts treated with the protein kinase inhibitor 6-dimethylaminopurine (6-DMAP).
- Assembly of nuclei in these extracts to observe DNA replication initiation and progression.
- Cell cycle analysis to determine the activity phase of the putative replication factor.
Main Results:
- 6-DMAP treated extracts inhibit DNA replication initiation, arresting nuclei in G2.
- A chromatin-modifying factor, active in early G1 before nuclear envelope assembly, was identified.
- This factor, incapable of nuclear entry, supports only one round of replication and is inactive during metaphase.
- The factor is rapidly activated upon exit from metaphase.
Conclusions:
- The identified factor functions as a Replication Licensing Factor (RLF), explaining once-per-cell-cycle DNA replication.
- RLF activity is cell cycle-regulated, ensuring pre-replicative chromatin modification occurs only after mitosis.
- This discovery provides a mechanistic basis for the strict control of eukaryotic DNA replication.
Related Concept Videos
01:02The DNA Replication Fork
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:38S-Cdk Initiates DNA Replication
The cell cycle is a series of events leading to DNA duplication followed by the division of cell content to form two daughter cells. The cell cycle progresses in four stages—the cell increases in size (gap 1 or G1-phase), duplicates its DNA (synthesis or S-phase), prepares to divide (gap 2 or G2-phase), and divides (mitosis or M-phase).
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
01:02The DNA Replication Fork
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:38S-Cdk Initiates DNA Replication
The cell cycle is a series of events leading to DNA duplication followed by the division of cell content to form two daughter cells. The cell cycle progresses in four stages—the cell increases in size (gap 1 or G1-phase), duplicates its DNA (synthesis or S-phase), prepares to divide (gap 2 or G2-phase), and divides (mitosis or M-phase).
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.
Two states at the origin of replication
In eukaryotes, the initiation of replication occurs at many sites on the chromosomes, called the origins of replication.