polymerase

(noun)

Any of various enzymes that catalyze the formation of polymers of DNA or RNA using an existing strand of DNA or RNA as a template.

Related Terms

Examples of polymerase in the following topics:

  • Molecular Products from Microbes

    • Taq polymerase is an enzyme that was first isolated from the microbe Thermus aquaticus.
    • The isolation of this polymerase has resulted in the ability to perform polymerase chain reactions (PCR), a process used to amplify DNA segments, in a single step.
    • Prior to the isolation of Taq polymerase, a new DNA polymerase had to be added to the reaction after every cycle because of thermal denaturation.
    • Currently, Taq polymerase is manufactured and produced on a large scale and is available for commercial sale.
    • Describe how Taq polymerase, restriction enzymes and DNA ligase are used in molecular biology

  • Amplifying DNA: The Polymerase Chain Reaction

    • The polymerase chain reaction (PCR) is a method by which DNA is amplified.
    • Primers (short DNA fragments) containing sequences complementary to the target region, along with a DNA polymerase (after which the method is named) are key components to enable selective and repeated amplification.
    • Taq polymerase or another DNA polymerase with a temperature optimum at around 70 °C
    • Deoxynucleoside triphosphates (dNTPs; nucleotides containing triphosphate groups), the building-blocks from which the DNA polymerase synthesizes a new DNA strand
    • Extension/elongation step: The temperature at this step depends on the DNA polymerase used; Taq polymerase has its optimum activity temperature at 75-80 °C, and commonly a temperature of 72 °C is used with this enzyme.

  • Control of Transcription in Archaea

    • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria, with the archaean RNA polymerase and ribosomes being very close to their equivalents in eukaryotes.
    • Although archaea only have one type of RNA polymerase, its structure and function in transcription seems to be close to that of the eukaryotic RNA polymerase II, with similar protein assemblies (the general transcription factors) directing the binding of the RNA polymerase to a gene's promoter.

  • Verrucomicrobia

    • Support for this superphylum has been found by examining the RNA polymerase protein RpoB.
    • rpoB is the gene that encodes the β subunit of bacterial RNA polymerase.
    • RNA polymerase II (also called RNAP II and Pol II) is an enzyme found in eukaryotic cells.

  • Regulation of Sigma Factor Activity

    • Specifically, in bacteria, sigma factors are necessary for recognition of RNA polymerase to the gene promoter site.
    • The sigma factor allows the RNA polymerase to properly bind to the promoter site and initiate transcription which will result in the production of an mRNA molecule.
    • Once the role of the sigma factor is completed, the protein leaves the complex and RNA polymerase will continue with transcription.
    • The anti-sigma factors will bind to the RNA polymerase and prevent its binding to sigma factors present at the promoter site.

  • Repression of Anabolic Pathways

    • Transcription of a gene by RNA polymerase can be regulated by at least five mechanisms:
    • Specificity factors alter the specificity of RNA polymerase for a given promoter or set of promoters, making it more or less likely to bind to them (i.e. sigma factors used in prokaryotic transcription).
    • General transcription factors position RNA polymerase at the start of a protein-coding sequence and then release the polymerase to transcribe the mRNA.
    • Activators enhance the interaction between RNA polymerase and a particular promoter, encouraging the expression of the gene.
    • Activators do this by increasing the attraction of RNA polymerase for the promoter, through interactions with subunits of the RNA polymerase or indirectly by changing the structure of the DNA.

  • Chromosomes and DNA Replication in the Archaea

    • The circular chromosomes contain multiple origins of replication, using DNA polymerases that resemble eukaryotic enzymes.
    • It is structurally similar to viral RNA dependent RNA polymerases, reverse transcriptases, cyclic nucleotide generating cyclases, and DNA polymerases involved in DNA replication and repair.

  • Inhibiting Nucleic Acid Synthesis

    • For example, the antimicrobial rifampin binds to DNA-dependent RNA polymerase, thereby inhibiting the initiation of RNA transcription.
    • In addition to DNA polymerase, the enzyme that synthesizes the new DNA by adding nucleotides matched to the template strand, a number of other proteins are associated with the fork and assist in the initiation and continuation of DNA synthesis.
    • RNA Polymerase, an enzyme that produces RNA, from T. aquaticus pictured during elongation.

  • Archaeal Gene Regulation

    • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria, with the archaean RNA polymerase and ribosomes being very close to their equivalents in eukaryotes.
    • Although archaea only have one type of RNA polymerase, its structure and function in transcription seems to be close to that of the eukaryotic RNA polymerase II, with similar protein assemblies (the general transcription factors) directing the binding of the RNA polymerase to a gene's promoter.

  • DNA Sequencing Based on Sanger Dideoxynucleotides

    • This method is based on amplification of the DNA fragment to be sequenced by DNA polymerase and incorporation of modified nucleotides - specifically, dideoxynucleotides (ddNTPs).
    • The classical chain-termination method requires a single-stranded DNA template, a DNA primer, a DNA polymerase, normal deoxynucleotidetriphosphates (dNTPs), and modified nucleotides (dideoxyNTPs) that terminate DNA strand elongation .
    • These chain-terminating nucleotides lack a 3'-OH group required for the formation of a phosphodiester bond between two nucleotides, causing DNA polymerase to cease extension of DNA when a ddNTP is incorporated.
    • The ddNTPs may be radioactively or fluorescently labelled for detection in automated sequencing machines.The DNA sample is divided into four separate sequencing reactions, containing all four of the standard deoxynucleotides (dATP, dGTP, dCTP and dTTP) and the DNA polymerase.