Somasekhar G, Szybalski W
Gene. 1983 Dec;26(2-3):291-4. doi: 10.1016/0378-1119(83)90199-3.
To locate the site required for transcription antitermination by the gene Q product, we constructed a plasmid containing the p'R promoter, the t'R1 terminator, and gene galK. We measured the galK expression in response to the lambda Q product supplied in trans, while deleting various portions of lambda DNA adjacent to p'R. The presence of the lambda p'R promoter together with the downstream DNA coding for only a 34-bp segment of 5'-proximal 6S RNA permits antitermination to occur, whereas deletions removing this segment abolish antitermination, as measured by galK expression, but do not affect the p'R promoter. Thus the 34-bp segment must contain the p'R-distal (right) boundary of the Q-specific recognition site qut (Fig. 1). The Q-mediated antitermination appears to be p'R-qut specific but not t'R1 specific, since it does not operate with the pp-t'R1 assembly, but is also effective with terminators other than t'R1, e.g., with the combination of the p'R-qut-tL3 modules.
为了定位基因Q产物进行转录抗终止所需的位点，我们构建了一个质粒，该质粒包含p'R启动子、t'R1终止子和galK基因。我们在反式提供λQ产物的情况下测量galK的表达，同时删除与p'R相邻的λDNA的各个部分。λp'R启动子与仅编码5'-近端6S RNA 34个碱基对片段的下游DNA一起存在时允许抗终止发生，而通过galK表达测量，删除该片段会消除抗终止，但不影响p'R启动子。因此，34个碱基对的片段必须包含Q特异性识别位点qut的p'R远端（右侧）边界（图1）。Q介导的抗终止似乎是p'R-qut特异性的，而不是t'R1特异性的，因为它不能与pp-t'R1组合起作用，但对t'R1以外的终止子也有效，例如，与p'R-qut-tL3模块组合。
