URA3
Encyclopedia
URA3 is gene on Chromosome V in Saccharomyces (yeast). Its systematic name is YEL021W.
URA3 is a gene
that encodes orotidine 5-phosphate decarboxylase (ODCase), which is an enzyme
that catalyzes one reaction involved in the synthesis of pyrimidine
ribonucleotides in yeast RNA.
Loss of ODCase activity leads to a lack of cell growth unless uracil
or uridine
is added to the media. When you add URA3 gen in auxotrophic bacterials they can now grow (positive selection). In contrast, if 5-FOA (5-Fluoroorotic acid) is added to the media, the ODCase of prototrophic bacterials can convert 5-FOA into the toxic compound (a suicide inhibitor) 5-fluorouracil causing death (negative selection
).
Since URA3 allows for both positive and negative selection, it has been developed as a genetic marker for DNA transformations and other genetic techniques in bacteria and many fungal species. It is one of the most important genetic markers in yeast
genetic modification.
URA3 is a gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
that encodes orotidine 5-phosphate decarboxylase (ODCase), which is an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that catalyzes one reaction involved in the synthesis of 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...
ribonucleotides in yeast RNA.
Loss of ODCase activity leads to a lack of cell growth unless uracil
Uracil
Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine, cytosine, and guanine. In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine.Uracil is a common and...
or uridine
Uridine
Uridine is a molecule that is formed when uracil is attached to a ribose ring via a β-N1-glycosidic bond.If uracil is attached to a deoxyribose ring, it is known as a deoxyuridine....
is added to the media. When you add URA3 gen in auxotrophic bacterials they can now grow (positive selection). In contrast, if 5-FOA (5-Fluoroorotic acid) is added to the media, the ODCase of prototrophic bacterials can convert 5-FOA into the toxic compound (a suicide inhibitor) 5-fluorouracil causing death (negative selection
Negative selection
Negative selection may refer to:*Negative selection , in natural selection it refers to the selective removal of rare alleles that are deleterious...
).
Since URA3 allows for both positive and negative selection, it has been developed as a genetic marker for DNA transformations and other genetic techniques in bacteria and many fungal species. It is one of the most important genetic markers in 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...
genetic modification.