期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：15
页码：4609-4612
DOI：10.1073/pnas.79.15.4609
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Plasmids pNF1337 and pNF1341, which contain part of the L10 operon including the RNA polymerase beta-subunit gene, have been used as templates in vitro to investigate expression of the beta-subunit gene. For these studies, the synthesis of the first dipeptide of the beta subunit, fMet-Val, was measured instead of that of the entire protein. By using this dipeptide system, we studied the effects of RNA polymerase holoenzyme and L factor (nus A gene product) on fMET-Val synthesis and compared the relative effects of the primary and secondary promoters in the L10 operon on expression of the beta-subunit gene. The results show that the inhibitory effect of RNA polymerase on beta-subunit synthesis and the stimulatory effect of L factor occur before formation of the first dipeptide bond. In this in vitro system, the secondary promoters account for about 50% of the total fMet-Val synthesized. Although the primary promoter is sensitive to guanosine 5'-diphosphate 3'-diphosphate in vitro, the secondary promoters are not affected by this nucleotide.
