Polarity suppressors increase expression of the wild-type tryptophan operon of Escherichia coli
| Autor: | Laurence Jay Korn, Charles Yanofsky |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
Operator (biology)
Genotype Transcription Genetic Operon Polarity (physics) Biology Coliphages Frameshift mutation trp operon Species Specificity Acetyltransferases Structural Biology Escherichia coli Tryptophan Synthase Molecular Biology Anthranilate Synthase Structural gene Tryptophan Wild type Chromosome Mapping Molecular biology Galactosidases RNA Bacterial Mutation bacteria |
| Zdroj: | Journal of Molecular Biology. 103:395-409 |
| ISSN: | 0022-2836 |
| DOI: | 10.1016/0022-2836(76)90319-3 |
| Popis: | Three new polarity suppressors, selected to relieve the polar effect of nonsense mutations in the tryptophan (trp) and lactose (lac) operons of Escherichia coli, increase expression distal to nonsense mutations in both operons to a greater extent than suA. These suppressors relieve the polarity created by amber, ochre and frameshift mutations with equal efficiency. Two of the three polarity suppressors elevate enzyme synthesis in the wildtype trp operon two- and fivefold, respectively. The increase in enzyme levels is in each case correlated with increased levels and rates of synthesis of structural gene trp messenger RNA. Since expression of all genes is elevated, these findings suggest the existence of a site early in the wild-type trp operon that affects the extent of operon expression. We located the site affected by these two polarity suppressors between the operator and the first structural gene, trpE. Although the third polarity suppressor also relieves mutational polarity efficiently, it has no detectable effect on expression of the wild-type trp operon. |
| Databáze: | OpenAIRE |
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