title: Dramatic changes in DNA-binding specificity caused by single residue substitutions in an Arc/Mnt hybrid repressor.
abstract: Arc and Mnt are homologous repressors which recognize operator sequences that differ at 8-10 important positions. Nevertheless, single residue changes in an Arc/Mnt hybrid protein can switch DNA-binding specificity between the two operators and even allow one particular hybrid to bind strongly to both operators. The ability of single residue changes to radically alter binding specificity involves: 'master' residues that mediate some base contacts directly and some base contacts indirectly through residue-residue hydrogen bonds; identical residues which can make alternative sets of DNA contacts in the two operators; and amplification of the effect of each mutation because the proteins bind operator DNA as tetramers.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Raumann
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; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D012680:Sensitivity and Specificity
chemical_list: D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D004247:DNA