PMID:5330222
| Citation |
Müller-Hill, B (1966) Suppressible regulator constitutive mutants of the lactose system in Escherichia coli.J. Mol. Biol. 15:374-6 |
|---|---|
| Abstract |
No abstract in PubMed |
| Links | |
| Keywords |
Enzyme Repression; Escherichia coli; Galactosidases; Genetic Code; Guanidines; Lactose; Molecular Biology; Mutation; Purines; RNA, Messenger |
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Main Points of the Paper
- Suppressors of nonsense codons exist for the regulatory i gene of the lactose operon, thereby proving that the functional i product is a protein.
- Rationale: suppression of nonsense codons into amino acids occurs at the translational level
- Specific activity of β-galactosidase in the wild type is 12; in both the suppressible (but unsuppressed) constitutives 18,000.
- values in a large number of different su+ revertants from these two constitutive strains range from 600 to 2000, indicating incomplete suppression and the existence of different suppressors.
Materials and Methods Used
- Parent Strain: 112-12 (gal-cys-his-su-)
- gal- and cys-mutations are suppressible by the same suppressor(s)
- Mutagenesis using 2-aminopurine (2AP) or N-methyl-N'-nitro-N-nitrosguanidine
- ONPG solution to select for lac constitutive mutants
Phenotype Annotations
<protect>
| Species | Taxon ID | Strain | Gene (if known) | OMP | Phenotype | Details | Evidence | Notes |
|---|---|---|---|---|---|---|---|---|
|
Escherichia coli |
NCBI:562 |
112-12lacI-(c) |
su |
|
Growth |
colonies on D-galactose + L-histidine plates (revertants to su+) |
Plating Assay |
in text, pg. 374 |
|
Escherichia coli |
NCBI:562 |
112-12lacI-(c) |
lacI |
|
Expression |
decreased beta-galactosidase level (nonsense mutation present in lacI gets suppressed in the presence of su+) |
Biochemical Assay |
in text, pg. 374 |
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