Widdick D, Farez-Vidal E, Austin S, Dixon R
Nitrogen Fixation Laboratory, John Innes Centre, Norwich, UK.
FEBS Lett. 1998 Oct 16;437(1-2):70-4. doi: 10.1016/s0014-5793(98)01206-x.
The mutation S170A in the proposed nucleotide binding site of the transcriptional activator protein NTRC abolishes its ability to catalyse open promoter complex formation by the sigma(N)-RNA polymerase holoenzyme. NTRC(S170A) has significant ATPase activity, which, in contrast to the wild-type protein, is unaffected by phosphorylation or binding to enhancer sites on DNA. The mutant protein appears to oligomerise normally on DNA in response to phosphorylation but the ATPase activity is apparently not responsive to changes in oligomerisation state. The defect in transcriptional activation is discussed in relation to mutations in other sigma(N)-dependent activators.
转录激活蛋白NTRC的假定核苷酸结合位点中的S170A突变消除了其催化由σ(N)-RNA聚合酶全酶形成开放启动子复合物的能力。NTRC(S170A)具有显著的ATP酶活性，与野生型蛋白不同的是，它不受磷酸化或与DNA上增强子位点结合的影响。突变蛋白似乎在磷酸化作用下能正常在DNA上寡聚，但ATP酶活性显然对寡聚状态的变化没有反应。结合其他σ(N)依赖性激活因子中的突变讨论了转录激活缺陷。
