Difference between revisions of "PMID:5330222"

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(Main Points of the Paper)
(Table edited by Azweifel via TableEdit)
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NCBI:562
 
NCBI:562
 
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112-12''lac<sup>c</sup>'' (''gal-cys-his-su-'')
+
112-12''lacI<sup>-</sup><sup>(c)</sup>''  
 +
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 +
''su''
 +
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 +
 
 +
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 +
Growth
 +
|
 +
colonies on D-galactose + L-histidine plates (revertants to ''su<sup>+</sup>'')
 +
|
 +
Plating Assay
 +
|
 +
in text, pg. 374
 +
|-  
 +
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 +
''Escherichia coli''
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 +
NCBI:562
 +
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 +
112-12''lacI<sup>-</sup><sup>(c)</sup>''
 
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''lacI''
 
''lacI''
 
|
 
|
decreased beta-galactosidase activity
+
 
 
|
 
|
Metabolic Activity
+
Expression
 
|
 
|
decreased beta-galactosidase activity in the ''su+'' revertants compared to the ''su-'' parent
+
decreased beta-galactosidase level (nonsense mutation present in ''lacI'' gets suppressed in the presence of ''su<sup>+</sup>'')
 
|
 
|
 
Biochemical Assay
 
Biochemical Assay
 
|
 
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LacZ assay
+
in text, pg. 374
  
 
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Revision as of 17:18, 16 December 2010

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

PubMed

Keywords

Enzyme Repression; Escherichia coli; Galactosidases; Genetic Code; Guanidines; Lactose; Molecular Biology; Mutation; Purines; RNA, Messenger

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

Please list the materials and methods used in this paper (strains, plasmids, antibodies, etc).

  • Mutagenesis of E.coli strain 112-12 (gal-, cys-, his-, su)
    • Mutagen-producing agents: 2-aminopurine 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

</protect>

Notes