Gross G, Fields D A, Bautz E K
Mol Gen Genet. 1976 Sep 23;147(3):337-41. doi: 10.1007/BF00582886.
RNA polymerase isolated from ts XH56, a conditional lethal mutant unable to grow and synthesize RNA at 42 degrees, was found to be temperature sensitive in vitro. The mutation affects the beta' subunit as determined by mixed reconstitution of isolated subunits from wild-type and mutant enzyme. The mutant RNA polymerase is unstable; addition of glycerol stabilizes the enzyme and increases its activity on native DNA. In addition, the mutant enzymes is sensitive to high ionic strength. Both high temperature and high ionic strength do not affect chain elongation; thus, the mutation renders the enzyme unable either to bind to or melt out promotor sites. From these data we conclude that the beta' subunit plays an important role in promotor selection.
从ts XH56（一种在42摄氏度时无法生长和合成RNA的条件致死突变体）中分离出的RNA聚合酶，在体外被发现对温度敏感。通过对野生型和突变型酶的分离亚基进行混合重组确定，该突变影响β'亚基。突变的RNA聚合酶不稳定；添加甘油可使酶稳定并增加其对天然DNA的活性。此外，突变酶对高离子强度敏感。高温和高离子强度均不影响链延伸；因此，该突变使酶无法结合或解开启动子位点。根据这些数据我们得出结论，β'亚基在启动子选择中起重要作用。
