primase

DNAプライマーゼ

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/02/12 16:58:05」(JST)

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DNA primase, also called as DNA primerase, is an enzyme involved in the replication of DNA. DNA primase is a type of RNA polymerase which creates an RNA primer (later this RNA piece is removed by a 5' to 3' exonuclease); next, DNA polymerase uses the RNA primer to replicate ssDNA.

Primase catalyzes the synthesis of a short RNA (or DNA in some organisms ) segment called a primer complementary to a ssDNA template. Primase is of key importance in DNA replication because no known DNA polymerases can initiate the synthesis of a DNA strand without an initial RNA or DNA primer (for temporary DNA elongation).

Function

In bacteria, primase binds to the DNA helicase forming a complex called the primosome. Primase is activated by DNA helicase where it then synthesizes a short RNA primer approximately 11 ±1 nucleotides long, to which new nucleotides can be added by DNA polymerase.

The RNA segments are first synthesized by primase and then elongated by DNA polymerase. Then the DNA polymerase forms a protein complex with two primase subunits to form the alpha DNA Polymerase primase complex. Primase is one of the most error prone and slow polymerases. Primases in organisms such as E. coli, synthesize around 2000 to 3000 primers at the rate of one primer per second. Primase also acts as a halting mechanism to prevent the leading strand from outpacing the lagging strand by halting the progression of the replication fork. The rate determining step in primase is when the first phosphodiester bond is formed with the ssDNA. The crystal structure of primase in E. coli with core that contained the DnaG protein was determined in 2000. The DnaG and primase complex is cashew shaped and contains three subdomains. The central subdomain forms a toprim fold which is made of a mixture five beta sheets and six alpha helices. The toprim fold is used for binding regulators and metals. The primase uses a phosphotransfer domain for the transfer coordination of metals, which makes it distinct from other polymerases. The side subunits contain a NH2 and COOH terminal made of alpha helixes and beta sheets. The NH2 terminal interacts with a zinc binding domain and COOH-terminal region which interacts with DnaB-ID. The replication mechanisms differ between different bacteria and viruses where the primase covalently link to helicase in viruses such as the T7 bacteriophage. In viruses such as herpes simplex virus (HSV-1), primase can form complexes with helicase. The primase-helicase complex is used to unwind dsDNA and synthesizes the lagging strand using RNA primers The majority of primers synthesized by primase are two to three nucleotides long.

Types

• dnaG

External links

• Overview article on primase structure and function (1995)
• DNA Primase at the US National Library of Medicine Medical Subject Headings (MeSH)
• Proteopedia: Helicase-binding domain of Escherichia coli primase
• Proteopedia: Complex between the DnaB helicase and the DnaG primase

References

UpToDate Contents

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• 1. ヒトヘルペスウイルス6型感染症のウイルス学、病因、および疫学 virology pathogenesis and epidemiology of human herpesvirus 6 infection
• 2. 免疫正常患者における単純ヘルペスウイルス1型感染の治療 treatment of herpes simplex virus type 1 infection in immunocompetent patients
• 3. 性器単純ヘルペスウイルス感染の治療 treatment of genital herpes simplex virus infection

English Journal

• A structural view of bacterial DNA replication.

• , O O, A A, A A, h h, .
• Protein science : a publication of the Protein Society. 2019 Jun;28(6)990-1004.
• DNA replication mechanisms are conserved across all organisms. The proteins required to initiate, coordinate, and complete the replication process are best characterized in model organisms such as Escherichia coli. These include nucleotide triphosphate-driven nanomachines such as the DNA-unwinding h
• PMID 30945375

• RNA insertion in DNA as the imprint moiety: the fission yeast paradigm.

• , S S, J J, J J, h h, .
• Current genetics. 2019 May;().
• This review elaborates on the findings of a new report which possibly resolves the biochemical nature of a novel type of DNA imprint as ribonucleotide and the mechanism of its formation during cell differentiation in fission yeast. The process of mating-type switching in fission yeast, Schizosacchar
• PMID 31076844

• Defective DNA Polymerase α-Primase Leads to X-Linked Intellectual Disability Associated with Severe Growth Retardation, Microcephaly, and Hypogonadism.

• Van Esch H, Colnaghi R, Freson K, Starokadomskyy P, Zankl A, Backx L, Abramowicz I, Outwin E, Rohena L, Faulkner C, Leong GM, Newbury-Ecob RA, Challis RC, Õunap K, Jaeken J, Seuntjens E, Devriendt K, Burstein E, Low KJ, O'Driscoll M.
• American journal of human genetics. 2019 May;104(5)957-967.
• Replicating the human genome efficiently and accurately is a daunting challenge involving the duplication of upward of three billion base pairs. At the core of the complex machinery that achieves this task are three members of the B family of DNA polymerases: DNA polymerases α, δ, and ε. Collect
• PMID 31006512

Japanese Journal

• 植物のTWINKLE は葉緑体DNA 複製に関わるDNA プライマーゼか? : 細胞内局在の検討

• 京都産業大学総合学術研究所所報 9, 87-94, 2014-07
• NAID 110009808898

• 植物のTWINKLE は葉緑体DNA 複製に関わるDNA プライマーゼか?:アミノ酸配列の比較による検討

• 京都産業大学総合学術研究所所報 8, 49-55, 2013-07
• NAID 110009623842

• Xenopus laevis Ctc1-Stn1-Ten1 (xCST) protein complex is involved in priming DNA synthesis on single-stranded DNA template in Xenopus egg extract.

• The Journal of biological chemistry 287(1), 619-627, 2012-01-02
• NAID 120004287848

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「プライマーゼ」

「プライマーゼ」

　　[★] DNAプライマーゼ

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primase