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Isolation and analysis of arc repressor mutants: Evidence for an unusual mechanism of DNA binding
Author(s) -
Vershon Andrew K.,
Bowie James U.,
Karplus Theresa M.,
Sauer Robert T.
Publication year - 1986
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340010404
Subject(s) - repressor , dna , mutant , arc (geometry) , missense mutation , chemistry , lac repressor , binding site , bacteriophage , hmg box , genetics , biophysics , mutation , stereochemistry , biology , microbiology and biotechnology , dna binding protein , biochemistry , gene , gene expression , transcription factor , geometry , mathematics , escherichia coli
We have isolated 64 different missense mutations at 36 out of 53 residue positions in the Arc repressor of bacteriophage P22. Many of the mutant proteins with substitutions in the C‐terminal 40 residues of Arc have reduced intracellular levels and probably have altered structures or stabilities. Mutations in the N‐terminal ten residues of Arc cause large decreases in operator DNA binding affinity without affecting the ability of Arc to fold into a stable three‐dimensional structure. We argue that these N‐terminal residues are important for operator recognition but that they are not part of a conventional helix‐turn‐helix DNA binding structure. These results suggest that Arc may use a new mechanism for sequence specific DNA binding.