Hauser C A, Sharp J A, Hatfield L K, Hatfield G W
J Biol Chem. 1985 Feb 10;260(3):1765-70.
Synchronized single-round transcriptions, in vitro, from templates encoding the leader RNA of the ilvB and ilvGEDA operons result in the accumulation of a transcript consistent with RNA polymerase pausing after the 1:2 stem that could form in each of the leader RNAs. Addition of L-factor or guanosine 5'-diphosphate,3-diphosphate extended the pause half-life obtained with the ilvB template; addition of L-factor and guanosine 5'-diphosphate,3'-diphosphate together had an additive effect on the pause half-life. L-factor also extended the pause half-life of the pause obtained with the ilvGEDA template; however, addition of guanosine 5'-diphosphate,3'-diphosphate did not. The results obtained are consistent with the model for attenuation proposed by Yanofsky et al. (Yanofsky, C., Das, A., Fisher, R., Kolter, R., and Berlin, V. (1984) UCLA Symposium of Gene Expression (Hamer, D., and Rosenberg, M., eds) pp. 295-310, Alan R. Liss, Inc., New York) in which transcriptional pausing after the synthesis of the 1:2 stem-loop closely couples transcription and translation of the leader region.
在体外，对编码ilvB和ilvGEDA操纵子前导RNA的模板进行同步单轮转录，会积累一种转录本，该转录本与RNA聚合酶在每个前导RNA中可能形成的1:2茎环之后暂停的情况一致。添加L因子或鸟苷5'-二磷酸,3'-二磷酸可延长ilvB模板获得的暂停半衰期；同时添加L因子和鸟苷5'-二磷酸,3'-二磷酸对暂停半衰期有累加效应。L因子也延长了ilvGEDA模板获得的暂停半衰期；然而，添加鸟苷5'-二磷酸,3'-二磷酸则没有这种效果。所获得的结果与Yanofsky等人提出的衰减模型一致（Yanofsky, C., Das, A., Fisher, R., Kolter, R., and Berlin, V. (1984) UCLA Symposium of Gene Expression (Hamer, D., and Rosenberg, M., eds) pp. 295 - 310, Alan R. Liss, Inc., New York），在该模型中，1:2茎环合成后的转录暂停紧密耦合了前导区域的转录和翻译。
