The origin of replication (also called the replication origin) is a particular DNA sequence at which DNA replication is initiated. DNA replication may proceed from this point bidirectionally or unidirectionally. It has been suggested that DNA replicate, Replisome, Replication fork, Lagging strand, Leading strand be merged into this article or section. ...

The specific structure of the origin of replication varies somewhat from species to species, but all share some common characteristics such as rich in AT content. The origin of replication binds the pre-replication complex—a protein complex that recognizes, unwinds, and begins to copy DNA. A pre-replication complex is a protein complex that forms at the origin of replication during the initiation step of DNA replication. ...

Types

The two types of replication origin are :

• Narrow or broad host range
• High- or low-copy number

There are also significant differences between prokaryotic and eukaryotic origins of replication:

• Prokaryotes have a single circular molecule of DNA, and typically only a single origin of replication per circular chromosome.

• Eukaryotes often have multiple origins of replication on each chromosome. Having many origins of replication helps to speed the duplication of their (usually) much larger store of genetic material. The segment of DNA that is copied starting from each unique replication origin is called a replicon.

Origins of replication are typically assigned names containing ori. Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... A replicon is a DNA molecule or RNA molecule, or a region of DNA or RNA that replicates from a single origin of replication. ... Ori is the DNA sequence that signals for the origin of replication, sometimes refered to simply as origin. ...

Prokaryotic

The E. coli replication origin is known as oriC. In E. coli, the oriC consists of 13 mer repeats followed by 9 mer repeats. E. coli redirects here. ... E. coli redirects here. ...

A protein, DnaA would bind to the 9 mer repeats, and the DNA would then coil around the protein complex (many DnaA) forming a protein core.

This coiling stimulates the AT rich region in the 13 mer sequence to unwind, thus allowing enzymes and other factors to bind and replication would start.

Eukaryotic

In eukaryotes, the budding yeast, Saccharomyces cerevisiae, has the best characterised replication origins. These origins were first identified by their ability to support the replication of mini-chromosomes or plasmids, giving rise to the name Autonomously Replicating Sequences or ARS elements. Each budding yeast origin consists of a short (~11 bp) essential DNA sequence (called the ARS consensus sequence or ACS) that recruits replication proteins. Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... Binomial name Saccharomyces cerevisiae Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ... Figure 1 : Schematic drawing of a bacterium with plasmids enclosed. ... Binomial name Saccharomyces cerevisiae Meyen ex E.C. Hansen Saccharomyces cerevisiae is a species of budding yeast. ...

In other eukaryotes, including humans, the DNA sequences at the replication origins vary. Despite this sequence variation, all the origins form a base for assembly of a group of proteins known collectively as the pre-replication complex (pre-RC): Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... A pre-replication complex is a protein complex that forms at the origin of replication during the initiation step of DNA replication. ...

• First, the origin DNA is bound by the Origin Recognition Complex (ORC) which, with help from two further protein factors (Cdc6 and Cdt1), load the Mini Chromosome Maintenance (or MCM) protein complex.
• Once assembled, this complex of proteins indicates that the replication origin is ready for activation. Once the replication origin is activated, the cell's DNA will be replicated.

In metazoans, pre-RC formation is inhibited by the protein Geminin, which binds to and inactivates Cdt1. Regulation of replication, such as this, is important as it prevents the DNA from being replication more than once each cell cycle. ORC or Origin Recognition Complex is a multisubunit complex existing in the replication procedure of DNA. It marks the replication origin by binding to and marking ori sequences in all eukaryotes in an ATP-dependent manner. ... Cdc6 cell division cycle 6 homolog protein essential for DNA replication. ... Animalia redirects here. ... There are very few or no other articles that link to this one. ... The cell cycle, or cell-division cycle, is the series of events that take place in an eukaryotic cell between its formation and the moment it replicates itself. ...

External links

• MeSH Replication+Origin

The DNA Replication Origin Database, OriDB