T7 RNA polymerase
Encyclopedia
T7 RNA Polymerase is an RNA polymerase
from the T7 bacteriophage
that catalyzes the formation of RNA
in the 5'→ 3' direction.
. Nevertheless, many common functional features are shared with these more complex enzymes.
or spermidine
.
Homogeneously labeled single-stranded RNA can be generated with this system. Transcripts can be non-radioactively labeled to high specific activity with certain labeled nucleotides.
RNA polymerase
RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...
from the T7 bacteriophage
Bacteriophage
A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...
that catalyzes the formation of RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
in the 5'→ 3' direction.
Activity
T7 polymerase is extremely promoter-specific and only transcribes DNA downstream of a T7 promoter. The T7 polymerase also requires a DNA template and Mg2+ ion as cofactor for the synthesis of RNA. It has a very low error rate. T7 polymerase has a molecular weight of 99 kDa.Related proteins
Related family members include phage T3 and SP6 RNA polymerases, but this family is also related to the mitochondrial RNA polymerase. The T7 family of RNA polymerases is structurally and evolutionarily distinct from the multi-subunit family of RNA polymerases (including bacterial and eukaryotic sub-families). In contrast to bacterial RNA polymerases, T7 polymerase is not inhibited by the antibiotic rifampicinRifampicin
Rifampicin or rifampin is a bactericidal antibiotic drug of the rifamycin group. It is a semisynthetic compound derived from Amycolatopsis rifamycinica ...
. Nevertheless, many common functional features are shared with these more complex enzymes.
Application
In biotechnology applications, T7 RNA polymerase is commonly used to transcribe DNA that has been cloned into vectors that have two (different) phage promoters (e.g., T7 and T3, or T7 and SP6) in opposite orientation. RNA can be selectively synthesized from either strand of the insert DNA with the different polymerases. The enzyme is stimulated by BSABovine serum albumin
Bovine serum albumin is a serum albumin protein derived from cows. It is often used as a protein concentration standard....
or spermidine
Spermidine
Spermidine is a polyamine involved in cellular metabolism. Its known actions include:#Inhibition of neuronal nitric oxide synthase, nNOS#Assisting the in vitro process of transcribing RNA via stimulation of T4 polynucleotide kinase and T7 RNA polymerase activity; it binds to and precipitates DNA...
.
Homogeneously labeled single-stranded RNA can be generated with this system. Transcripts can be non-radioactively labeled to high specific activity with certain labeled nucleotides.