- THIS ARTICLE
- Full Text (PDF)
- Alert me when this article is cited
- Alert me if a correction is posted
- SERVICES
- Similar articles in this journal
- Similar articles in PubMed
- Alert me to new issues of the journal
- Download to citation manager
- Reprints & Permissions
- CITING ARTICLES
- Citing Articles via Google Scholar
- GOOGLE SCHOLAR
- Articles by Arvidson, D. N.
- Articles by Youderian, P.
- Search for Related Content
- PUBMED
- PubMed Citation
- Articles by Arvidson, D. N.
- Articles by Youderian, P.
Genetics, Vol 128, 29-35, Copyright © 1991
INVESTIGATIONS |
Mutant Tryptophan Aporepressors With Altered Specificities of Corepressor Recognition
D. N. Arvidson, M. Shapiro and P. Youderian
Present address: California Institute of Biological Research, 11099 N. Torrey Pines Road, La Jolla, California 92037.
The Escherichia coli trpR gene encodes tryptophan aporepressor, which binds the corepressor ligand, L-tryptophan, to form an active repressor complex. The side chain of residue valine 58 of Trp aporepressor sits at the bottom of the corepressor (L-tryptophan) binding pocket. Mutant trpR genes encoding changes of Val(58) to the other 19 naturally occurring amino acids were made. Each of the mutant proteins requires a higher intracellular concentration of tryptophan for activation of DNA binding than wild-type aporepressor. Whereas wild-type aporepressor is activated better by 5-methyltryptophan (5-MT) than by tryptophan, Ile(58) and other mutant aporepressors prefer tryptophan to 5-MT as corepressor, and Ala(58) and Gly(58) prefer 5-MT much more strongly than wild-type aporepressor in vivo. These mutant aporepressors are the first examples of DNA-binding proteins with altered specificities of cofactor recognition.