Array ( [0] => {{Short description|Class of enzymes which synthesize nucleic acid chains or polymers}} [1] => [[Image:Taq polimerase.png|thumb|Structure of [[Taq polymerase|Taq DNA polymerase]]]] [2] => [3] => In [[biochemistry]], a '''polymerase''' is an [[enzyme]] ([[Enzyme Commission number|EC]] 2.7.7.6/7/19/48/49) that synthesizes long chains of [[polymer]]s or [[nucleic acid]]s. [[DNA polymerase]] and [[RNA polymerase]] are used to assemble [[DNA]] and [[RNA]] molecules, respectively, by copying a DNA template strand using [[Base pair|base-pairing]] interactions or RNA by half ladder replication. [4] => [5] => A DNA polymerase from the [[thermophile|thermophilic]] bacterium, ''[[Thermus aquaticus]]'' (''Taq'') ([[Protein Data Bank|PDB]] [http://www.rcsb.org/pdb/cgi/explore.cgi?pid=288631034363198&pdbId=1BGX 1BGX], EC 2.7.7.7) is used in the [[polymerase chain reaction]], an important technique of [[molecular biology]]. [6] => [7] => A polymerase may be template-dependent or template-independent. [[Polynucleotide adenylyltransferase|Poly-A-polymerase]] is an example of template independent polymerase. [[Terminal deoxynucleotidyl transferase]] also known to have template independent and template dependent activities. [8] => [9] => ==Types== [10] => [11] => === By function === [12] => {| class="wikitable floatright" [13] => |+ Classes of Template dependent polymerase [14] => ! [15] => !DNA-polymerase [16] => !RNA-polymerase [17] => |- [18] => !Template is DNA [19] => |DNA dependent DNA-polymerase
or common [[DNA polymerases]] [20] => |DNA dependent RNA-polymerase
or common [[RNA polymerases]] [21] => |- [22] => !Template is RNA [23] => |RNA dependent DNA polymerase
or [[Reverse transcriptase]] [24] => |RNA dependent RNA polymerase
or [[RNA-dependent RNA polymerase|RdRp or RNA-replicase]] [25] => |} [26] => *[[DNA polymerase]] (DNA-directed DNA polymerase, DdDP) [27] => **Family A: [[DNA polymerase I]]; Pol [[POLG|γ]], [[POLQ|θ]], [[DNA polymerase nu|ν]] [28] => **Family B: [[DNA polymerase II]]; Pol [[DNA polymerase alpha|α]], [[DNA polymerase delta|δ]], [[DNA polymerase epsilon|ε]], [[REV3L|ζ]] [29] => **Family C: [[DNA polymerase III holoenzyme]] [30] => **Family X: Pol [[DNA polymerase beta|β]], [[DNA polymerase lambda|λ]], [[DNA polymerase mu|μ]] [31] => ***[[Terminal deoxynucleotidyl transferase]] (TDT), which lends diversity to antibody heavy chains.{{cite journal | vauthors = Loc'h J, Rosario S, Delarue M | title = Structural Basis for a New Templated Activity by Terminal Deoxynucleotidyl Transferase: Implications for V(D)J Recombination | journal = Structure | volume = 24 | issue = 9 | pages = 1452–63 | date = September 2016 | pmid = 27499438 | doi = 10.1016/j.str.2016.06.014 | doi-access = free }} [32] => **Family Y: [[DNA polymerase IV]] (DinB) and [[DNA polymerase V]] (UmuD'2C) - [[SOS response|SOS]] repair polymerases; Pol [[DNA polymerase eta|η]], [[POLI|ι]], [[POLK|κ]] [33] => *[[Reverse transcriptase]] (RT; RNA-directed DNA polymerase; RdDP) [34] => ** [[Telomerase]] [35] => *DNA-directed [[RNA polymerase]] (DdRP, RNAP) [36] => **Multi-subunit (msDdRP): [[RNA polymerase I]], [[RNA polymerase II]], [[RNA polymerase III]] [37] => **Single-subunit (ssDdRP): [[T7 RNA polymerase]], [[POLRMT]] [38] => **[[Primase]], [[PrimPol]] [39] => *[[RNA replicase]] (RNA-directed RNA polymerase, RdRP) [40] => **Viral (single-subunit) [41] => **Eukaryotic cellular (cRdRP; dual-subunit) [42] => *Template-less RNA elongation [43] => ** [[Polyadenylation]]: [[Polynucleotide adenylyltransferase|PAP]], [[Polynucleotide phosphorylase|PNPase]] [44] => {{clear|right}} [45] => [46] => === By structure === [47] => Polymerases are generally split into two superfamilies, the "right hand" fold ({{InterPro|IPR043502}}) 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.{{cite journal | vauthors = Hansen JL, Long AM, Schultz SC | title = Structure of the RNA-dependent RNA polymerase of poliovirus | journal = Structure | volume = 5 | issue = 8 | pages = 1109–22 | date = August 1997 | pmid = 9309225 | doi = 10.1016/S0969-2126(97)00261-X | doi-access = free }} The latter is seen in all multi-subunit RNA polymerases, in cRdRP, and in "family D" DNA polymerases found in archaea.{{cite journal | vauthors = Cramer P | title = Multisubunit RNA polymerases | journal = Current Opinion in Structural Biology | volume = 12 | issue = 1 | pages = 89–97 | date = February 2002 | pmid = 11839495 | doi = 10.1016/S0959-440X(02)00294-4 }}{{cite journal | vauthors = Sauguet L | title = The Extended "Two-Barrel" Polymerases Superfamily: Structure, Function and Evolution | journal = Journal of Molecular Biology | volume = 431 | issue = 20 | pages = 4167–4183 | date = September 2019 | pmid = 31103775 | doi = 10.1016/j.jmb.2019.05.017 | doi-access = free }} The "X" family represented by [[DNA polymerase beta]] has only a vague "palm" shape, and is sometimes considered a different superfamily ({{InterPro|IPR043519}}).{{cite journal | vauthors = Salgado PS, Koivunen MR, Makeyev EV, Bamford DH, Stuart DI, Grimes JM | title = The structure of an RNAi polymerase links RNA silencing and transcription | journal = PLoS Biology | volume = 4 | issue = 12 | pages = e434 | date = December 2006 | pmid = 17147473 | pmc=1750930 | doi = 10.1371/journal.pbio.0040434 | doi-access = free }} [48] => [49] => Primases generally don't fall into either category. Bacterial primases usually have the Toprim domain, and are related to [[topoisomerase]]s and mitochondrial helicase [[Twinkle (protein)|twinkle]].{{cite journal | vauthors = Aravind L, Leipe DD, Koonin EV | title = Toprim--a conserved catalytic domain in type IA and II topoisomerases, DnaG-type primases, OLD family nucleases and RecR proteins | journal = Nucleic Acids Research | volume = 26 | issue = 18 | pages = 4205–13 | date = September 1998 | pmid = 9722641 | pmc = 147817 | doi = 10.1093/nar/26.18.4205 }} 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.{{cite journal | vauthors = Iyer LM, Koonin EV, Leipe DD, Aravind L | title = Origin and evolution of the archaeo-eukaryotic primase superfamily and related palm-domain proteins: structural insights and new members | journal = Nucleic Acids Research | volume = 33 | issue = 12 | pages = 3875–96 | date = 2005 | pmid = 16027112 | pmc = 1176014 | doi = 10.1093/nar/gki702 }} [50] => [51] => [52] => File:WikiHandDNAPolII.png|Right hand structure of Bacteriophage RB69, a family B DdRP. [53] => [54] => [55] => [56] => [57] => [58] => ==See also== [59] => * [[Central dogma of molecular biology]] [60] => * [[Exonuclease]] [61] => * [[Ligase]] [62] => * [[Nuclease]] [63] => * [[Polymerase chain reaction|PCR]] [64] => * [[Poly (ADP-ribose) polymerase|PARP]] [65] => * [[Reverse transcription polymerase chain reaction]] [66] => * [[RNA ligase (ATP)]] [67] => [68] => == References == [69] => {{Reflist}} [70] => [71] => ==External links== [72] => [73] => {{DNA replication}} [74] => {{Kinases}} [75] => {{Enzymes}} [76] => {{Portal bar|Biology|border=no}} [77] => {{Authority control}} [78] => [79] => [[Category:EC 2.7.7]] [80] => [[Category:Enzymes]] [] => )
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Polymerase

Polymerase is an enzyme that plays a crucial role in DNA replication, transcription, and repair processes. It is responsible for catalyzing the synthesis of DNA or RNA molecules using a template strand as a guide.

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It is responsible for catalyzing the synthesis of DNA or RNA molecules using a template strand as a guide. Polymerases are classified into different types based on their functions and the type of nucleic acid they synthesize. In DNA replication, DNA polymerases replicate the double-stranded DNA molecule by adding new nucleotides to the growing daughter strand. They ensure the accuracy of replication by proofreading and correcting errors. Different DNA polymerases are involved in different stages of replication, such as initiation, elongation, and termination. RNA polymerases are responsible for transcribing DNA into RNA during the process of transcription. They possess similar catalytic mechanisms to DNA polymerases but have unique properties that allow them to distinguish between different types of DNA sequences and initiate transcription at specific locations. There are multiple types of RNA polymerases, each responsible for synthesizing different types of RNA molecules. Besides replication and transcription, polymerases also play a crucial role in DNA repair mechanisms. They are involved in repairing damaged DNA by removing damaged or incorrect nucleotides and replacing them with the correct ones. Polymerases have been extensively studied and characterized, leading to the discovery of various DNA and RNA polymerase families. These families include DNA polymerase I, II, III, and IV in prokaryotes, and RNA polymerase I, II, and III in eukaryotes, among others. Each polymerase family has distinct characteristics and functions. Understanding the structure and function of polymerases has significant implications in various fields, including genetics, molecular biology, and medicine. Polymerases are targets for drug development, as inhibiting their activity can disrupt DNA replication or transcription, leading to the inhibition of cancer cell growth. Additionally, polymerase chain reaction (PCR), a widely used technique in molecular biology, relies on the activity of DNA polymerases to amplify specific DNA sequences for various applications. Overall, polymerases are essential enzymes involved in many fundamental cellular processes, and their study continues to provide insights into the complex mechanisms of DNA replication, transcription, and repair.

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