biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ...

, a polymerase is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

( EC 2.7.7.6/7/19/48/49) that synthesizes long chains of

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

s or

nucleic acid Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a pentose, 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nuclei ...

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create t ...

and

RNA polymerase In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template. Using the e ...

are used to assemble

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

and

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

molecules, respectively, by copying a DNA template strand using

base-pairing A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

interactions or RNA by half ladder replication. A DNA polymerase from the

thermophilic A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bact ...

bacterium, ''

Thermus aquaticus ''Thermus aquaticus'' is a species of bacteria that can tolerate high temperatures, one of several thermophile, thermophilic bacteria that belong to the ''Deinococcota'' phylum. It is the source of the heat-resistant enzyme Taq polymerase, ''Taq' ...

'' (''Taq'') ( PDBbr>1BGX
EC 2.7.7.7) is used in the

polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to make millions to billions of copies of a specific DNA sample rapidly, allowing scientists to amplify a very small sample of DNA (or a part of it) sufficiently to enable detailed st ...

, an important technique of

molecular biology Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...

. A polymerase may be template-dependent or template-independent. Poly-A-polymerase is an example of template independent polymerase.

Terminal deoxynucleotidyl transferase Terminal deoxynucleotidyl transferase (TdT), also known as DNA nucleotidylexotransferase (DNTT) or terminal transferase, is a specialized DNA polymerase expressed in immature, pre-B, pre-T lymphoid cells, and acute lymphoblastic leukemia/lymphom ...

also known to have template independent and template dependent activities.

By function

(DNA-directed DNA polymerase, DdDP) **Family A:

DNA polymerase I DNA polymerase I (or Pol I) is an enzyme that participates in the process of prokaryotic DNA replication. Discovered by Arthur Kornberg in 1956, it was the first known DNA polymerase (and the first known of any kind of polymerase). It was init ...

; Pol γ, θ, ν **Family B:

DNA polymerase II DNA polymerase II (also known as DNA Pol II or Pol II) is a prokaryote, prokaryotic DNA-dependent DNA polymerase encoded by the PolB gene. DNA Polymerase II is an 89.9-kDa protein and is a member of the B family of DNA polymerases. It was origin ...

; Pol α, δ, ε, ζ **Family C:

DNA polymerase III holoenzyme DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNA replication. It was discovered by Thomas Kornberg (son of Arthur Kornberg) and Malcolm Gefter in 1970. The complex has high processivity (i.e. the number ...

**Family X: Pol β, λ, μ ***

(TDT), which lends diversity to antibody heavy chains. **Family Y:

DNA polymerase IV DNA polymerase IV is a prokaryotic polymerase that is involved in mutagenesis and is encoded by the ''dinB'' gene. It exhibits no 3′→5′ exonuclease (proofreading) activity and hence is error prone. In ''E. coli'', DNA polymerase IV (Pol 4) ...

(DinB) and

DNA polymerase V DNA Polymerase V (Pol V) is a polymerase enzyme involved in DNA repair mechanisms in bacteria, such as ''Escherichia coli''. It is composed of a UmuD' homodimer and a UmuC monomer, forming the UmuD'2C protein complex. It is part of the Y-family ...

(UmuD'2C) -

SOS SOS is a Morse code distress signal (), used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line (), to indicate that the Morse code equivalents for the individual letters of "SOS" a ...

repair polymerases; Pol η, ι, κ *

Reverse transcriptase A reverse transcriptase (RT) is an enzyme used to convert RNA genome to DNA, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, by retrotransposon mobi ...

(RT; RNA-directed DNA polymerase; RdDP) **

Telomerase Telomerase, also called terminal transferase, is a ribonucleoprotein that adds a species-dependent telomere repeat sequence to the 3' end of telomeres. A telomere is a region of repetitive sequences at each end of the chromosomes of most euka ...

*DNA-directed

(DdRP, RNAP) **Multi-subunit (msDdRP):

RNA polymerase I RNA polymerase 1 (also known as Pol I) is, in higher eukaryotes, the polymerase that only transcribes ribosomal RNA (but not 5S rRNA, which is synthesized by RNA polymerase III), a type of RNA that accounts for over 50% of the total RNA synthesiz ...

RNA polymerase II RNA polymerase II (RNAP II and Pol II) is a Protein complex, multiprotein complex that Transcription (biology), transcribes DNA into precursors of messenger RNA (mRNA) and most small nuclear RNA (snRNA) and microRNA. It is one of the three RNA pol ...

RNA polymerase III In eukaryote cells, RNA polymerase III (also called Pol III) is a protein that transcribes DNA to synthesize 5S ribosomal RNA, tRNA, and other small RNAs. The genes transcribed by RNA Pol III fall in the category of "housekeeping" genes whose ex ...

**Single-subunit (ssDdRP):

T7 RNA polymerase T7 RNA Polymerase is an RNA polymerase from the T7 bacteriophage that catalyzes the formation of RNA from DNA in the 5'→ 3' direction. Activity T7 polymerase is extremely promoter-specific and transcribes only DNA downstream of a T7 promo ...

POLRMT DNA-directed RNA polymerase, mitochondrial is an enzyme that in humans is encoded by the ''POLRMT'' gene. Function This gene encodes a mitochondrial DNA-directed RNA polymerase. The gene product is responsible for mitochondrial gene expressio ...

Primase DNA primase is an enzyme involved in the replication of DNA and is a type of RNA polymerase. Primase catalyzes the synthesis of a short RNA (or DNA in some living organisms) segment called a primer complementary to a ssDNA (single-stranded ...

PrimPol PrimPol is a protein encoded by the ''PRIMPOL'' gene in humans. PrimPol is a eukaryotic protein with both DNA polymerase and DNA Primase activities involved in translesion DNA synthesis. It is the first eukaryotic protein to be identified wit ...

RNA replicase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand complementary to a given RNA template. This is in contrast to ...

(RNA-directed RNA polymerase, RdRP) **Viral (single-subunit) **Eukaryotic cellular (cRdRP; dual-subunit) *Template-less RNA elongation **

Polyadenylation Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euka ...

: PAP, PNPase

By structure

Polymerases are generally split into two superfamilies, the "right hand" fold () and the "double psi

beta barrel In protein structures, a beta barrel (β barrel) is a beta sheet (β sheet) composed of tandem repeats that twists and coils to form a closed toroidal structure in which the first strand is bonded to the last strand (hydrogen bond). Beta-strands ...

" (often simply "double-barrel") fold. The former is seen in almost all DNA polymerases and almost all viral single-subunit polymerases; they are marked by a conserved "palm" domain. The latter is seen in all multi-subunit RNA polymerases, in cRdRP, and in "family D" DNA polymerases found in archaea. The "X" family represented by

DNA polymerase beta DNA polymerase beta, also known as POLB, is an enzyme present in eukaryotes. In humans, it is encoded by the ''POLB'' gene. Function In eukaryotic cells, DNA polymerase beta (POLB) performs base excision repair (BER) required for DNA mainte ...

has only a vague "palm" shape, and is sometimes considered a different superfamily (). Primases generally don't fall into either category. Bacterial primases usually have the Toprim domain, and are related to

topoisomerase DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues in ...

s and mitochondrial helicase

twinkle Twinkle may refer to: * Twinkling, the variation of brightness of distant objects People * Twinkle (singer) (1948–2015), born Lynn Annette Ripley, English singer-songwriter * Twinkle Bajpai, Indian singer, television and film actress * Twinkl ...

. Archae and eukaryotic primases form an unrelated AEP family, possibly related to the polymerase palm. Both families nevertheless associate to the same set of helicases. File:WikiHandDNAPolII.png, Right hand structure of Bacteriophage RB69, a family B DdRP.

References

External links

{{Authority control EC 2.7.7 Enzymes

By function

By structure

See also

References

External links