title: Isolation and analysis of arc repressor mutants: evidence for an unusual mechanism of DNA binding.
abstract: 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.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: A K
authors.initials: AK
authors.lastname: Vershon
authors.forename: J U
authors.initials: JU
authors.lastname: Bowie
authors.forename: T M
authors.initials: TM
authors.lastname: Karplus
authors.forename: R T
authors.initials: RT
authors.lastname: Sauer
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D009875:Operator Regions, Genetic; D011487:Protein Conformation; D011489:Protein Denaturation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins