Two Extracytoplasmic Function Sigma Subunits, ςE and ςFecI, of Escherichia coli: Promoter Selectivity and Intracellular Levels
Two Extracytoplasmic Function Sigma Subunits, ςE and ςFecI, of Escherichia coli: Promoter Selectivity and Intracellular Levels
复制标题
DOI：
10.1128/jb.182.4.1181-1184.2000
复制
发表时间：
2000-02
影响因子：
3.2
通讯作者：
H. Maeda;M. Jishage;T. Nomura;N. Fujita;A. Ishihama
中科院分区：
文献类型：
--
作者：
H. Maeda;M. Jishage;T. Nomura;N. Fujita;A. Ishihama
利用体外转录系统和多种启动子分析了大肠杆菌RNA聚合酶的两个胞质外功能亚家族β-FecI（β-FecI 24）和β-FecI（β-FecI 18）的启动子选择性。大肠杆菌全酶仅识别已知的同源启动子rpoEP 2、rpoHP 3和degP，而大肠杆菌FecI仅识别一个已知的同源启动子fecA。严格的启动子识别特性的ESTE和ESTFecI是类似的其他次要的ESTFecI亚基。高浓度的谷氨酸增强了E β E和E β FecI的转录，就像其他次要的谷氨酸亚基一样。E. FecI转录的最适温度较低，约为25°C，这显然与E.大肠杆菌在低温条件下。通过定量Western印迹分析，未诱导的稳态培养的E.大肠杆菌W3110（A型）中的蛋白质含量分别为0.7 ~ 2.0和0.1 ~ 0.2 fmol/μg总蛋白（或3 ~ 9和0.4 ~ 0.9分子/细胞），低于大肠杆菌W3110（A型）中主要亚基含量的1%。
ABSTRACT The promoter selectivity of two extracytoplasmic function (ECF) subfamily ς subunits, ςE (ς24) and ςFecI (ς18), of Escherichia coli RNA polymerase was analyzed by using an in vitro transcription system and various promoters. The EςEholoenzyme recognized only the known cognate promoters,rpoEP2, rpoHP3, and degP, and the EςFecI recognized only one known cognate promoter,fecA. The strict promoter recognition properties of ςE and ςFecI are similar to those of other minor ς subunits. Transcription by EςE and EςFecI was enhanced by high concentrations of glutamate, as in the case of other minor ς subunits. The optimum temperature for transcription by EςFecI was low, around 25°C, apparently in agreement with the high rate of iron sequestration byE. coli at low temperatures. By quantitative Western blot analysis, the intracellular levels of ςE and ςFecI in the uninduced steady-state culture of E. coli W3110 (type A) were determined to be 0.7 to 2.0 and 0.1 to 0.2 fmol per μg of total proteins (or 3 to 9 and 0.4 to 0.9 molecules per cell), respectively, and less than 1% of the level of the major ς70 subunit.