In vitro synthesis of the first dipeptide of the beta subunit of Escherichia coli RNA polymerase.

S. Peacock, Y. Cenatiempo, N. Robakis, N. Brot, H. Weissbach

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18 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)4609-4612
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume79
Issue number15
DOIs
StatePublished - Aug 1982

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