DNA polymerase III

DNAポリメラーゼIII

WordNet

1. the 9th letter of the Roman alphabet (同)i
2. the 4th letter of the Roman alphabet (同)d
3. an enzyme that catalyzes the formation of new DNA and RNA from an existing strand of DNA or RNA

PrepTutorEJDIC

1. 『私は』私が
2. iodineの化学記号
3. deuteriumの化学記号
4. deoxyribonucleic acidディオキシリボ核酸

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/20 05:42:29」(JST)

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Schematic picture of DNA polymerase III* (with subunits).

Pol III can also refer to HNoMS Pol III, a Norwegian guard vessel from WWII

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 nucleotides added per binding event) and, specifically referring to the replication of the E.coli genome, works in conjunction with four other DNA polymerases (Pol I, Pol II, Pol IV, and Pol V). Being the primary holoenzyme involved in replication activity, the DNA Pol III holoenzyme also has proofreading capabilities that correct replication mistakes by means of exonuclease activity working 3'→5'. DNA Pol III is a component of the replisome, which is located at the replication fork.

Components

The replisome is composed of the following:

• 2 DNA Pol III enzymes, each comprising α, ε and θ subunits. (It has been proven that there is a third copy of Pol III at the replisome.)
  • the α subunit (encoded by the dnaE gene) has the polymerase activity.
  • the ε subunit (dnaQ) has 3'→5' exonuclease activity.
  • the θ subunit (holE) stimulates the ε subunit's proofreading.
• 2 β units (dnaN) which act as sliding DNA clamps, they keep the polymerase bound to the DNA.
• 2 τ units (dnaX) which acts to dimerize two of the core enzymes (α, ε, and θ subunits).
• 1 γ unit (also dnaX) which acts as a clamp loader for the lagging strand Okazaki fragments, helping the two β subunits to form a unit and bind to DNA. The γ unit is made up of 5 γ subunits which include 3 γ subunits, 1 δ subunit (holA), and 1 δ' subunit (holB). The δ is involved in copying of the lagging strand.
• Χ (holC) and Ψ (holD) which form a 1:1 complex and bind to γ or τ. X can also mediate the switch from RNA primer to DNA.

Activity

DNA polymerase III synthesizes base pairs at a rate of around 1000 nucleotides per second. DNA Pol III activity begins after strand separation at the origin of replication. Because DNA synthesis cannot start de novo, an RNA primer, complementary to part of the single-stranded DNA, is synthesized by primase (an RNA polymerase):

("!" for RNA, '"$" for DNA, "*" for polymerase)

--------> 
         * * * *
! ! ! !  _ _ _ _    
_ _ _ _ | RNA   |   <--ribose (sugar)-phosphate backbone
G U A U | Pol   |   <--RNA primer
* * * * |_ _ _ _|   <--hydrogen bonding
C A T A G C A T C C <--template ssDNA (single-stranded DNA)
_ _ _ _ _ _ _ _ _ _ <--deoxyribose (sugar)-phosphate backbone
$ $ $ $ $ $ $ $ $ $

Addition onto 3'OH

As replication progresses and the replisome moves forward, DNA polymerase III arrives at the RNA primer and begins replicating the DNA, adding onto the 3'OH of the primer:

         * * * *
! ! ! !  _ _ _ _
_ _ _ _ | DNA   |   <--ribose (sugar)-phosphate backbone
G U A U | Pol   |   <--RNA primer
* * * * |_III_ _|   <--hydrogen bonding
C A T A G C A T C C <--template ssDNA (single-stranded DNA)
_ _ _ _ _ _ _ _ _ _ <--deoxyribose (sugar)-phosphate backbone
$ $ $ $ $ $ $ $ $ $

Synthesis of DNA

DNA polymerase III will then synthesize a continuous or discontinuous strand of DNA, depending if this is occurring on the leading or lagging strand (Okazaki fragment) of the DNA. DNA polymerase III has a high processivity and therefore, synthesizes DNA very quickly. This high processivity is due in part to the β-clamps that "hold" onto the DNA strands.

        ----------->
                    * * * *
! ! ! ! $ $ $ $ $ $ _ _ _ _
_ _ _ _ _ _ _ _ _ _| DNA   |   <--deoxyribose (sugar)-phosphate backbone
G U A U C G T A G G| Pol   |   <--RNA primer
* * * * * * * * * *|_III_ _|   <--hydrogen bonding
C A T A G C A T C C <--template ssDNA (single-stranded DNA)
_ _ _ _ _ _ _ _ _ _ <--deoxyribose (sugar)-phosphate backbone
$ $ $ $ $ $ $ $ $ $

Removal of primer

After replication of the desired region, the RNA primer is removed by DNA polymerase I via the process of nick translation. The removal of the RNA primer allows DNA ligase to ligate the DNA-DNA nick between the new fragment and the previous strand. DNA polymerase I & III, along with many other enzymes are all required for the high fidelity, high-processivity of DNA replication.

See also

• DNA replication
• DNA polymerase
• Beta clamp
• Clamping down on pathogenic bacteria – how to shut down a key DNA polymerase complex

References

External links

• Overview at Oregon State University
• DNA Polymerase III at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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English Journal

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• Tannous J1, Atoui A2, El Khoury A3, Kantar S3, Chdid N3, Oswald IP4, Puel O4, Lteif R3.
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• Due to the occurrence and spread of the fungal contaminants in food and the difficulties to remove their resulting mycotoxins, rapid and accurate methods are needed for early detection of these mycotoxigenic fungi. The polymerase chain reaction and the real time PCR have been widely used for this pu
• PMID 25998812

• Myocerebrohepatopathy spectrum disorder due to POLG mutations: A clinicopathological report.

• Montassir H1, Maegaki Y2, Murayama K3, Yamazaki T4, Kohda M5, Ohtake A4, Iwasa H5, Yatsuka Y6, Okazaki Y7, Sugiura C8, Nagata I9, Toyoshima M10, Saito Y8, Itoh M11, Nishino I12, Ohno K8.
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• We report on the clinical, neuropathological, and genetic findings of a Japanese case with myocerebrohepatopathy spectrum (MCHS) disorder due to polymerase gamma (POLG) mutations. A girl manifested poor sucking and failure to thrive since 4months of age and had frequent vomiting and developmental re
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• Grabbing the genome by the NADs.

• Matheson TD1, Kaufman PD.
• Chromosoma.Chromosoma.2015 Jul 15. [Epub ahead of print]
• The regions of the genome that interact frequently with the nucleolus have been termed nucleolar-associated domains (NADs). Deep sequencing and DNA-fluorescence in situ hybridization (FISH) experiments have revealed that these domains are enriched for repetitive elements, regions of the inactive X c
• PMID 26174338

Japanese Journal

• 第550回大阪歯科学会例会

• 歯科医学 79(2), 77-77, 2016
• NAID 130005286366

• Systematic identification of synthetic lethal mutations with reduced-genome <i>Escherichia coli</i>: synthetic genetic interactions among <i>yoaA</i>, <i>xthA</i> and <i>holC</i> related to survival from MMS exposure

• Genes & Genetic Systems 91(3), 183-188, 2016
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• Systematic identification of synthetic lethal mutations with reduced-genome Escherichia coli: synthetic genetic interactions among yoaA, xthA and holC related to survival from MMS exposure

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Related Links

• DNA polymerase III - 岡山大学工学部 生物機能工学科

DNA polymerase III 複製の際、DNAを合成 asymmetric dimer (非対称2量体) で作用する 2ヶの酵素がそれぞれのDNA鎖の複製を同時におこなう dnaG タンパク質によりprimerが合成されると、DNApolymerase III が結合する｡α, ε, θ core ...

• POLIII BETA SUBUNIT - California Lutheran University

I. Introduction The remarkable, donut-shaped molecule to your left is the beta subunit of DNA polymerase III of E. coli (pol III). This subunit provides for the remarkable processivity of the holoenzyme during DNA replication ...

Related Pictures

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★リンクテーブル★

リンク元	「Pol III」「DNA polymerase delta」「DNAポリメラーゼIII」
拡張検索	「DNA polymerase III holoenzyme」
関連記事	「D」「II」「I」「DNA」

「Pol III」

　　[★]

• RNAポリメラーゼIII、DNAポリメラーゼIII

関

DNA polymerase delta、DNA polymerase III、RNA polymerase III

「DNA polymerase delta」

　　[★] DNAポリメラーゼδ

関

DNAポリメラーゼIII、DNA polymerase III、Pol III

「DNAポリメラーゼIII」

　　[★]

英

DNA polymerase III

関

DNAポリメラーゼ

「DNA polymerase III holoenzyme」

　　[★] DNAポリメラーゼIIIホロ酵素

「D」

　　[★]

• アスパラギン酸
• ジヒドロウリジン
• 遠位の distal,
• うつ病 depression
• 下行結腸 descending colon(大腸内視鏡検査の結果を記載するときに用いる)

　 　

「II」

　　[★]

• 蛍光像増倍管 image intensifier
• インスリン分泌指数 インスリノゲニック・インデックス insulinogenic index
• 黄疸指数 icterus index

「I」

　　[★]

• イソロイシン isoleucine
• イノシン inosine
• 阻害剤 inhibitor
• iodine
• ヨード iodide
• I因子 factor I

　 　 　

「DNA」

　　[★]

英

deoxyribonucleic acid

同

デオキシリボ核酸

関

リボ核酸 RNA