Mutagenesis of amino acid residues required for binding of corepressors to the purine repressor

Kang Yell Choi, Fu Lu, Howard Zalkin

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The corepressor-binding domain of the Escherichia coli purine repressor (PurR) is homologous with several periplasmic sugar-binding proteins. Four amino acids in PurR were investigated for a role in binding of corepressors. Three of the residues, Asp146, Arg196 and Asp275, are conserved in periplasmic binding proteins for ribose, glucose/galactose, and arabinose and function to bind sugars. A fourth amino acid, Trp147, required for corepressor binding to PurR, corresponds to residues in glucose/galactose, ribose, and arabinose that also have a role in sugar binding. The four mutations that were constructed perturbed the binding of both hypoxanthine and guanine thus providing evidence for a single corepressor site/PurR subunit. The decreased corepressor binding affinity resulted in reduced affinity of mutant repressors for operator DNA in vitro and decreased capacity for repression in vivo. The corepressor-binding site in PurR appears to be similar to the conserved ligand-binding sites in the three periplasmic sugar-binding proteins and in the LacI family of repressors.

Original languageEnglish
Pages (from-to)24066-24072
Number of pages7
JournalJournal of Biological Chemistry
Volume269
Issue number39
Publication statusPublished - 1994 Sep 30

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Co-Repressor Proteins
Mutagenesis
Periplasmic Binding Proteins
Amino Acids
Sugars
Arabinose
Ribose
Galactose
Carrier Proteins
Binding Sites
Glucose
Hypoxanthine
Guanine
Escherichia coli
purine
Ligands
Mutation
DNA

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

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abstract = "The corepressor-binding domain of the Escherichia coli purine repressor (PurR) is homologous with several periplasmic sugar-binding proteins. Four amino acids in PurR were investigated for a role in binding of corepressors. Three of the residues, Asp146, Arg196 and Asp275, are conserved in periplasmic binding proteins for ribose, glucose/galactose, and arabinose and function to bind sugars. A fourth amino acid, Trp147, required for corepressor binding to PurR, corresponds to residues in glucose/galactose, ribose, and arabinose that also have a role in sugar binding. The four mutations that were constructed perturbed the binding of both hypoxanthine and guanine thus providing evidence for a single corepressor site/PurR subunit. The decreased corepressor binding affinity resulted in reduced affinity of mutant repressors for operator DNA in vitro and decreased capacity for repression in vivo. The corepressor-binding site in PurR appears to be similar to the conserved ligand-binding sites in the three periplasmic sugar-binding proteins and in the LacI family of repressors.",
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Mutagenesis of amino acid residues required for binding of corepressors to the purine repressor. / Choi, Kang Yell; Lu, Fu; Zalkin, Howard.

In: Journal of Biological Chemistry, Vol. 269, No. 39, 30.09.1994, p. 24066-24072.

Research output: Contribution to journalArticle

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