A polymerase is an
enzyme (
EC 2.7.7.6/7/19/48/49) that synthesizes long chains of
polymers or
nucleic acid
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...
s.
DNA polymerase 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 synthesizes RNA from a DNA template.
Using the enzyme helicase, RNAP locally opens the ...
are used to assemble
DNA and
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
molecules, respectively, by copying a DNA template strand using
base-pairing interactions or RNA by half ladder replication.
A DNA polymerase from the
thermophilic bacterium, ''
Thermus aquaticus'' (''Taq'') (
PDBbr>
1BGX EC 2.7.7.7) is used in the
polymerase chain reaction, an important technique of
molecular biology.
A polymerase may be template dependent or template independent.
Poly-A-polymerase is an example of template independent polymerase.
Terminal deoxynucleotidyl transferase also known to have template independent and template dependent activities.
Types
By function
*
DNA polymerase (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 initiall ...
; Pol
γ,
θ,
ν
**Family B:
DNA polymerase II; 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 of ...
**Family X: Pol
β,
λ,
μ
***
Terminal deoxynucleotidyl transferase (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' Protein dimer, homodimer and a UmuC monomer, forming the UmuD'2C protein complex. It is part of ...
(UmuD'2C) -
SOS
is a Morse code distress signal (), used internationally, that was originally established for maritime use. In formal notation is written with an overscore line, to indicate that the Morse code equivalents for the individual letters of "SOS" ...
repair polymerases; Pol
η,
ι,
κ
*
Reverse transcriptase
A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genomes, ...
(RT; RNA-directed DNA polymerase; RdDP)
**
Telomerase
*DNA-directed
RNA polymerase
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template.
Using the enzyme helicase, RNAP locally opens the ...
(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 III
**Single-subunit (ssDdRP):
T7 RNA polymerase,
POLRMT
**
Primase,
PrimPol
*
RNA replicase (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 euk ...
:
PAP,
PNPase
By structure
Polymerases are generally split into two superfamilies, the "right hand" fold () and the "double psi
beta barrel" (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 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 i ...
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 Khanna, Indian movie actress
* Twinkle Bajpai, female conte ...
. 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.
See also
*
Central dogma of molecular biology
The central dogma of molecular biology is an explanation of the flow of genetic information within a biological system. It is often stated as "DNA makes RNA, and RNA makes protein", although this is not its original meaning. It was first stated by ...
*
Exonuclease
Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3′ or the 5′ end occurs. Its close relative is the ...
*
Ligase
*
Nuclease
A nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds between nucleotides of nucleic acids. Nucleases variously effect single and double stranded breaks in their ta ...
*
PCR PCR or pcr may refer to:
Science
* Phosphocreatine, a phosphorylated creatine molecule
* Principal component regression, a statistical technique
Medicine
* Polymerase chain reaction
** COVID-19 testing, often performed using the polymerase chain r ...
*
PARP
*
Reverse transcription polymerase chain reaction
Reverse transcription polymerase chain reaction (RT-PCR) is a laboratory technique combining reverse transcription of RNA into DNA (in this context called complementary DNA or cDNA) and amplification of specific DNA targets using polymerase cha ...
*
RNA ligase (ATP)
In enzymology, an RNA ligase (ATP) () is an enzyme that catalyzes the chemical reaction
:ATP + (ribonucleotide)n + (ribonucleotide)m \rightleftharpoons AMP + diphosphate + (ribonucleotide)n+m
The 3 substrates of this enzyme are ATP, (ribonuc ...
References
External links
{{Portal bar, Biology, border=no
EC 2.7.7
Enzymes
