A permutational approach toward protein-DNA recognition

Lixuan Huang, Takashi Sera, Peter G. Schultz

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


The cI repressor of bacteriophage 434, known as 434 repressor, binds to 14-bp operator sequences by means of a helix-turn-helix motif. To probe the requirements for selective DNA recognition by this class of DNA binding proteins, as well as to generate new proteins with altered specificities, a library of ≃3 x 106 mutants was generated that contains all permutations of five residues in the recognition helix (helix 3) of the repressor. These mutants were then selected in vivo for their ability to bind both wild-type (WT) and mutant operator sequences. The results of the selection demonstrate that four of these residues-Gln28, Gln29, Ser30, and Gln33-play a critical role in recognition of the WT operator. A number of repressors with mutations at Thr27 showed altered DNA binding affinities and specificities. The approach described here may also prove useful in studies of DNA recognition by other classes of DNA binding proteins.

Original languageEnglish
Pages (from-to)3969-3973
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number9
Publication statusPublished - Apr 26 1994
Externally publishedYes

ASJC Scopus subject areas

  • General


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