title: The Mnt repressor of bacteriophage P22: role of C-terminal residues in operator binding and tetramer formation.
abstract: A set of C-terminal deletion mutants of the Mnt repressor of bacteriophage P22 has been constructed, and the corresponding truncated proteins have been purified. A truncated protein lacking the three C-terminal residues, Lys80-Thr81-Thr82, binds operator DNA with an affinity near wild type and has a normal tetrameric structure. Loss of the next residue, Lys79, causes a 600-fold decrease in operator affinity, but the truncated protein is still tetrameric. Further sequential deletions of Tyr78 and Leu77 cause modest decreases in operator affinity, but the truncated proteins are now dimeric. These results indicate that Lys79 is an important determinant of the high affinity of Mnt repressor for operator DNA and that Tyr78 is an important determinant of tetramer formation by Mnt repressor.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: K L
authors.initials: KL
authors.lastname: Knight
authors.forename: R T
authors.initials: RT
authors.lastname: Sauer
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D005796:Genes; D005814:Genes, Viral; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics* / Q000302:isolation & purification; D012483:Salmonella Phages / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics* / Q000302:isolation & purification; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D046911:Macromolecular Substances; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins