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How lac repressor recognizes lac operator.

1978; National Academy of Sciences; Volume: 75; Issue: 8 Linguagem: Inglês

10.1073/pnas.75.8.3578

1091-6490

David V. Goeddel, Daniel G. Yansura, Marvin H. Caruthers,

Advanced biosensing and bioanalysis techniques

Nucleotide analogs were substituted for unmodified nucleotides at specific sites in the lac operator sequence by a combination of chemical and enzymatic procedures. The nitrocellulose filter assay was used to study the interactions of these modified operators with wild-type (SQ) and tight-binding (QX86) lac repressors. These studies implicate directly the 5 methyl of thymine and the 2 amino of guanine as important operator-repressor contact sites. Furthermore, when these findings are combined with published results from other laboratories, a model for the lac operator-lac repressor interaction can be derived. Two important postulates follow from this model. (i) The repressor interacts at specific and defined sites with the N7 of guanine, the 5 methyl of thymine, the 2 amino of guanine, and the central major groove of the operator. (ii) The repressor binds to one side of the operator.