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Nat Struct Biol. 1995 Dec;2(12):1115-22.

Dramatic changes in DNA-binding specificity caused by single residue substitutions in an Arc/Mnt hybrid repressor.

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Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.


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.

[Indexed for MEDLINE]

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