Autonomously replicating sequence
Encyclopedia
An autonomously replicating sequence (ARS) contains the origin of replication
in the yeast
genome
. It contains four regions (A, B1, B2, and B3), named in order of their effect on plasmid
stability; when these regions are mutated, replication does not initiate.
Element A is highly conserved, consisting of the consensus sequence:
5'- T/A T T T A Y R T T T T/A -3'
(where Y is either pyrimidine
and R is either purine
). When this element is mutated, the ARS loses all activity.
As seen above the ARS are considerably A-T rich which makes it easy for replicative proteins to disrupt the H-bonding in that area. ORC protein complex (Origin Recognition Complex
) binds to the ARS during DNA Replication
allowing replicative proteins access to the ARS.
Mutational analysis for the yeast ARS elements have shown that any mutation in the B1, B2 and B3 regions result in a reduction of function of the ARS element. A mutation in the A region results in a complete loss of function.
Origin of replication
The origin of replication is a particular sequence in a genome at which replication is initiated. This can either be DNA replication in living organisms such as prokaryotes and eukaryotes, or RNA replication in RNA viruses, such as double-stranded RNA viruses...
in the yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
. It contains four regions (A, B1, B2, and B3), named in order of their effect on plasmid
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...
stability; when these regions are mutated, replication does not initiate.
Element A is highly conserved, consisting of the consensus sequence:
5'- T/A T T T A Y R T T T T/A -3'
(where Y is either pyrimidine
Pyrimidine
Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring...
and R is either purine
Purine
A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....
). When this element is mutated, the ARS loses all activity.
As seen above the ARS are considerably A-T rich which makes it easy for replicative proteins to disrupt the H-bonding in that area. ORC protein complex (Origin Recognition Complex
Origin Recognition Complex
ORC or Origin Recognition Complex is a multi-subunit DNA binding complex that binds in all eukaryotes in an ATP-dependent manner to origins of replication....
) binds to the ARS during DNA Replication
DNA replication
DNA replication is a biological process that occurs in all living organisms and copies their DNA; it is the basis for biological inheritance. The process starts with one double-stranded DNA molecule and produces two identical copies of the molecule...
allowing replicative proteins access to the ARS.
Mutational analysis for the yeast ARS elements have shown that any mutation in the B1, B2 and B3 regions result in a reduction of function of the ARS element. A mutation in the A region results in a complete loss of function.