Mahoney M E, Wulff D L
Genetics. 1987 Apr;115(4):591-5. doi: 10.1093/genetics/115.4.591.
The dya5 mutation, a C----T change at position -43 of the lambda pRE promoter, results in a twofold increase in pRE activity in vivo. Smaller increases in pRE activity are found for the dya2 mutation, a T----C change at position -1 of pRE, and the dya3 mutation, an A----G change at +5 of pRE. The mutant pRE promoters retain complete dependence on cII protein for activity. These observations argue, at least for pRE-like promoters, that promoter activities are influenced by nucleotide sequences at least eight nucleotides to the 5'-side of the conventional -35 region consensus sequence, and by nucleotide sequences near the start-site of transcription. Although Hawley and McClure (1983) found A-T pairs more frequently than G-TC pairs in the region of -40 to -45 of prokaryotic promoters, other mutations that change a G-TC pair to an A-T pair at positions -41, -44 and -45 of pRE do not result in increased promoter activity. We also found that a T----C change at positions -42 results in a mild decrease in promoter activity. These observations argue that Ts at positions -42 and -43 of pRE are required for maximum promoter activity, but do not support the hypothesis that As and Ts in the -40 and -45 region generally lead to higher promoter activities.
dya5突变是λ pRE启动子-43位的C→T变化，导致体内pRE活性增加两倍。对于dya2突变（pRE -1位的T→C变化）和dya3突变（pRE +5位的A→G变化），pRE活性有较小程度的增加。突变的pRE启动子的活性仍然完全依赖于cII蛋白。这些观察结果表明，至少对于类似pRE的启动子来说，启动子活性受常规-35区共有序列5'端至少八个核苷酸处的核苷酸序列以及转录起始位点附近的核苷酸序列影响。尽管霍利和麦克卢尔（1983年）发现在原核启动子-40至-45区域中A - T对比G - TC对更常见，但在pRE的-41、-44和-45位将G - TC对改变为A - T对的其他突变并不会导致启动子活性增加。我们还发现-42位的T→C变化会导致启动子活性略有下降。这些观察结果表明，pRE的-42和-43位的T是最大启动子活性所必需的，但不支持-40和-45区域中的A和T通常会导致更高启动子活性的假设。
