Mechanism of dnaB protein action. IV. General priming of DNA replication by dnaB protein and primase compared with RNA polymerase.
Mechanism of dnaB protein action. IV. General priming of DNA replication by dnaB protein and primase compared with RNA polymerase.
复制标题
dnaB 蛋白的作用机制。
DOI：
10.1016/s0021-9258(19)69397-x
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
A. Kornberg
中科院分区：
文献类型：
--
作者：
K. Arai;A. Kornberg
dnaB蛋白和引发酶的通用引发系统（Arai，K.，和Kornberg，A.等人（1979）Proc. Acad. Sci.联合S. A. 76，4308-4312）与RNA聚合酶引发相比显示出许多显著差异。一般的引发系统主要在单链区域（S）处启动，仅对单链DNA（单链DNA和均聚物）有活性，并被单链DNA结合蛋白（SSB）抑制。转录本只有10到60个残基长。相比之下，RNA聚合酶的RNA引发起始于未被SSB去稳定化的碱基配对区域（Geider，K.，Beck，E.，和Szier，H.等人（1978）Proc. Acad. Sci.联合S. A. 76，645-649），并且未用SSB包被的DNA上的转录物通常更长。一般来说，ATP（或GTP）有三种功能：（i）对dnaB蛋白质的变构作用，其中非水解类似物腺苷-5 '-O-（3 '-硫代三磷酸）（或鸟苷-5 ′-O-（3 ′-硫代三磷酸）可以取代，（ii）引物合成的起始，其可以掺入脱氧核苷酸以及核糖核苷酸，和（iii）引物的延伸，其中β，γ-亚氨基类似物可以替代ATP（或GTP）。ATP对RNA聚合酶的变构效应尚未得到证实，核糖核苷酸和脱氧核糖核苷酸的杂合转录物的简易合成也未得到证实。
The general priming system of dnaB protein and primase (Arai, K., and Kornberg, A. (1979) Proc. Natl. Acad. Sci. U. S. A. 76, 4308-4312) when compared with priming by RNA polymerase shows a number of striking differences. The general priming system is initiated primarily at single-stranded region(S), being active only on single-stranded DNAs (phages and homopolymers) and inhibited by single-stranded DNA binding protein (SSB). Transcripts are only 10 to 60 residues long. By contrast, RNA priming by RNA polymerase is initiated at base-paired regions that are not destabilized by SSB (Geider, K., Beck, E., and Schaller, H. (1978) Proc. Natl. Acad. Sci. U. S. A. 76, 645-649) and transcripts on DNA not coated with SSB are generally longer. In general priming, ATP (or GTP) has three functions: (i) an allosteric effect on dnaB protein in which the nonhydrolyzed analogs adenosine-5'-O-(3'-thiotriphosphate) (or guanosine-5'-O-(3'-thiotriphosphate) can substitute, (ii) initiation of primer synthesis which can incorporate deoxy-, as well as ribonucleotides, and (iii) elongation of the primer, in which the beta, gamma-imido analog can replace ATP (or GTP). An allosteric effect of ATP on RNA polymerase has not been demonstrated, nor has the facile synthesis of hybrid transcripts of ribo- and deoxyribonucleotides.