Dramatic changes in DNA-binding specificity caused by single residue substitutions in an Arc/Mnt hybrid repressor.
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.
Raumann
B E
BE
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Knight
K L
KL
Sauer
R T
RT
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
D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D004247:DNA