ISSN:
1617-4623
Keywords:
Catabolite activator protein (CAP)
;
Transcription activator
;
Protein-protein interaction
;
Positive control mutants
;
DNA-binding protein
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Single amino acid substitutions for residue Glu171 in helix E of the catabolite gene activator protein (CAP) of Escherichia coli have been reported to abolish activation of transcription without impairing binding to the CAP site of the lac promoter. The negative charge of Glu171 was proposed to transmit the activating signal from CAP to RNA polymerase. However, this idea has been challenged by later work. We set up a system to re-examine this issue. We analysed the ability of mutant CAP-E 171 L and CAP-E 171 K proteins to bind a nearconsensus CAP site in vivo and found it to be diminished fourfold relative to wild type in each case. Activation of lac transcription by these mutant proteins remains the same as with wild-type CAP. Thus our results confirm that Glu171 in helix E of CAP is not involved directly in the activation of transcription. Yet CAP-E171K does not activate transcription as well as wild-type CAP under all circumstances. Possible reasons for this absence of activation are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00279542
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