Raskin C A, Diaz G A, McAllister W T
Morse Institute of Molecular Biology and Genetics, Department of Microbiology and Immunology, State University of New York Health Science Center, Brooklyn 11203-2098.
Proc Natl Acad Sci U S A. 1993 Apr 15;90(8):3147-51. doi: 10.1073/pnas.90.8.3147.
The amino acid at position 748 in T7 RNA polymerase (RNAP) functions to discriminate base pairs at positions -10 and -11 in the promoter. We have constructed a series of T7 RNAP mutants having all possible amino acid substitutions at this position. Surprisingly, most (13/19) substitutions result in active RNAPs, and many of these exhibit altered promoter specificities. Identification of mutant RNAPs with altered specificities expands the repertoire of highly specific phage RNAPs that are available for use in phage RNAP-based transcription systems and highlights the complexity of sequence-specific DNA recognition.
T7 RNA聚合酶（RNAP）中第748位的氨基酸负责区分启动子中-10和-11位的碱基对。我们构建了一系列在此位置具有所有可能氨基酸替换的T7 RNAP突变体。令人惊讶的是，大多数（13/19）替换产生了活性RNAP，其中许多表现出改变的启动子特异性。鉴定具有改变特异性的突变RNAP扩展了可用于基于噬菌体RNAP的转录系统的高特异性噬菌体RNAP的种类，并突出了序列特异性DNA识别的复杂性。
