Brown K L, Whiteley H R
Department of Microbiology, University of Washington, Seattle 98195.
J Bacteriol. 1990 Dec;172(12):6682-8. doi: 10.1128/jb.172.12.6682-6688.1990.
A crystal protein gene of Bacillus thuringiensis subsp. kurstaki HD-1-Dipel is transcribed in vivo from two overlapping promoters that are activated at different times during sporulation. We reported earlier (K. L. Brown and H. R. Whiteley, Proc. Natl. Acad. Sci. USA 85:4166-4170, 1988) that an RNA polymerase containing a sigma subunit with an apparent Mr of 35,000 can transcribe in vitro from the promoter utilized from early to midsporulation. We now report the isolation of an RNA polymerase containing a sigma subunit with an Mr of ca. 28,000; this polymerase activates transcription in vitro from the promoter used from mid- to late sporulation. This form of RNA polymerase also directs transcription in vitro from promoters preceding two other crystal protein genes and a gene coding for a spore coat protein. On the basis of a comparison of the four promoters, we propose the following consensus sequence for the -10 region recognized by RNA polymerase containing the Mr-28,000 sigma subunit: 5'-TNATANNaTGag-3'. No consensus sequence could be derived for the -35 region. When the N-terminal amino acid sequence of the sigma 28 polypeptide was aligned with the amino acid sequences of known sigma subunits, significant homology was found with the N terminus of the mature form of the sigma K subunit of RNA polymerase isolated from sporulating cells of Bacillus subtilis.
苏云金芽孢杆菌库斯塔克亚种HD - 1 - Dipel的一种晶体蛋白基因在体内由两个重叠启动子转录，这两个启动子在芽孢形成过程中的不同时间被激活。我们先前报道过（K. L. 布朗和H. R. 怀特利，《美国国家科学院院刊》85:4166 - 4170，1988），一种含有表观分子量为35,000的σ亚基的RNA聚合酶能够在体外从芽孢形成早期到中期所利用的启动子进行转录。我们现在报道分离出一种含有表观分子量约为28,000的σ亚基的RNA聚合酶；这种聚合酶在体外激活从芽孢形成中期到后期所使用的启动子的转录。这种形式的RNA聚合酶还在体外指导另外两个晶体蛋白基因以及一个编码芽孢衣蛋白的基因之前的启动子的转录。基于对这四个启动子的比较，我们提出了含有分子量为28,000的σ亚基的RNA聚合酶所识别的 - 10区域的如下共有序列：5'-TNATANNaTGag-3'。无法推导 - 35区域的共有序列。当将σ28多肽的N端氨基酸序列与已知σ亚基的氨基酸序列比对时，发现与从枯草芽孢杆菌芽孢形成细胞中分离出的RNA聚合酶的σK亚基成熟形式的N端有显著同源性。
