Isolation and analysis of arc repressor mutants: evidence for an unusual mechanism of DNA binding |
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Authors: | A K Vershon J U Bowie T M Karplus R T Sauer |
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Institution: | Department of Biology, Massachusetts Institute of Technology, Cambridge 02139. |
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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. |
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Keywords: | mutant proteins protein stability operator binding |
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