RNA聚合酶
RNA聚合酶Ⅰ
聚合酶
RNA依赖性RNA聚合酶
分子生物学
生物
RNA聚合酶Ⅱ
抄写(语言学)
转录因子ⅡD
T7 RNA聚合酶
RNA聚合酶Ⅲ
核糖核酸
RNA聚合酶Ⅱ全酶
发起人
噬菌体
DNA
基因
生物化学
大肠杆菌
基因表达
哲学
语言学
作者
Bin Zhu,Stanley Tabor,Desislava Raytcheva,Alfredo J. Hernandez,Jonathan King,Charles C. Richardson
标识
DOI:10.1074/jbc.m112.442350
摘要
A single subunit DNA-dependent RNA polymerase was identified and purified to apparent homogeneity from cyanophage Syn5 that infects the marine cyanobacteria Synechococcus. Syn5 is homologous to bacteriophage T7 that infects Escherichia coli. Using the purified enzyme its promoter has been identified by examining transcription of segments of Syn5 DNA and sequencing the 5'-termini of the transcripts. Only two Syn5 RNAP promoters, having the sequence 5'-ATTGGGCACCCGTAA-3', are found within the Syn5 genome. One promoter is located within the Syn5 RNA polymerase gene and the other is located close to the right genetic end of the genome. The purified enzyme and its promoter have enabled a determination of the requirements for transcription. Unlike the salt-sensitive bacteriophage T7 RNA polymerase, this marine RNA polymerase requires 160 mm potassium for maximal activity. The optimal temperature for Syn5 RNA polymerase is 24 °C, much lower than that for T7 RNA polymerase. Magnesium is required as a cofactor although some activity is observed with ferrous ions. Syn5 RNA polymerase is more efficient in utilizing low concentrations of ribonucleotides than T7 RNA polymerase.
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