Operator regions, nucleotide sequences

Table 8.1 The nucleotide sequences of the three protein-binding regions ORl, OR2, and OR3 of the operator of bacteriophage lambda...

The bond of the receptor dimer with the nucleotide sequence of the HRE in the promoter region of the gene is what directs the assembly of the proteins (up to 19) that yields the transcription machinery. The operation of the machinery depends on the continual, sequential reestablishment of protein-protein contacts. Each new interaction depends on whether the previous proteins had assembled themselves correctly in such a way that the protein under consideration does not bind unless the prior interactions have created the appropriate surface of contact. 

Regulation of expression, particularly transcription, is commonly coordinated by several nucleotide sequences associated with the gene in question. Some of these elements include promoters, operators, terminators as well as structurally-diverse intergenic regions (see the Sect. 3.1.1). The gene and its associated elements... 

The operator site of the lac operon has been extensively studied (Figure 31.4). The nucleotide sequence of the operator site shows a nearly perfect inverted repeat, indicating that the DNA in this region has an approximate twofold axis of... 

Two classes of constitutive lac mutants that result in expression of the lac operon even in the absence of inducer (A) The lac operator mutants that change the nucleotide sequence within the Lac repressor binding site, a region that contains an inverted repeat sequence. (B) The lac repressor (LacI) mutants that alter the amino-acid sequence within the DNA binding domain of the Lac repressor and thereby disrupt DNA binding function. 

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