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RNA hairpin loopsrepress proteinsynthesis morestrongly thanhammerhead ribozymes Horace R. DrewDenise LewyJason Conaty1999 год

RNA hairpin loops repress protein synthesis more strongly than hammerhead ribozymes
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Аннотация: A general study has been carried out to determine how well hammerhead ribozymes might reduce levels of specific protein synthesis in living cells, compared with RNA hairpin loops as stable but noncleaving controls. Four different experiments are described. First, a wide variety of hammerhead ribozymes, as well as hairpin loops, was cloned into a gene‐expression cassette for β‐galactosidase, upstream of the coding sequences for that reporter gene, and expressed from plasmids in several strains of Escherichia coli . The results show that ribozymes, when acting intramolecularly in E. coli , do not significantly reduce the amount of protein synthesized from any construct. As a control, long RNA hairpin loops do greatly reduce the amount of protein made. Secondly, we studied the transcription–translation of these same plasmids in a cell extract from E. coli . Once again, hammerhead ribozymes show no effect on levels of β‐galactosidase, whereas long RNA hairpin loops produce a strong reduction, by apparent attentuation at the level of translation. Thirdly, we added an SV40 promoter to each plasmid, in order to study the effects of these gene‐regulators on protein synthesis in Chinese hamster ovary cells. Here active intramolecular ribozymes produce a slight reduction in β‐galactosidase, whereas long RNA hairpin loops produce an even stronger reduction than before. Those hairpin loops apparently induce degradation of their own mRNA in Chinese hamster ovary cells, by a mechanism not seen in E. coli . Finally, analyses of total RNA by S1‐trimming show that hammerhead ribozymes will self‐cleave a mRNA by a total of no more than 45–50% in E. coli , compared with 70–80% in vitro . Other analyses using Northern blotting were unable to detect any ribozyme cleavage in E. coli or Chinese hamster ovary cells. In summary, the ability of hammerhead ribozymes to reduce protein synthesis appears weak or nonexistent in all the cellular systems tested. By comparison, long RNA hairpin loops reduce protein synthesis strongly: by an apparent attentuation mechanism in E. coli or by a novel degradation of their own mRNA in Chinese hamster ovary cells.
Год издания: 1999
Авторы: Horace R. Drew, Denise Lewy, Jason Conaty, Keith N. Rand, Philip Hendry, Trevor Lockett
Издательство: Wiley
Источник: European Journal of Biochemistry
Ключевые слова: RNA and protein synthesis mechanisms, Advanced biosensing and bioanalysis techniques, Bacteriophages and microbial interactions
Другие ссылки: European Journal of Biochemistry (HTML)
PubMed (HTML)