What happens when tetracycline binds to the repressor protein?

When tetracycline binds to the repressor protein, it prevents the repressor from binding to the operator. This inhibition is crucial because the repressor's primary function is to block transcription of the target genes by physically obstructing RNA polymerase from attaching to the promoter region of the operon. By preventing this binding, tetracycline essentially allows for gene transcription to proceed, thus facilitating the expression of the genes controlled by that operon. This mechanism is particularly relevant in bacterial systems where tetracycline acts as an antibiotic to disrupt normal protein synthesis by allowing the transcription of genes that might otherwise be silenced by the repressor.

The presence of tetracycline alters the interaction between the repressor and the operator, leading to a significant change in gene expression and demonstrating the antibiotic's effectiveness in combating bacterial infections by inhibiting their ability to synthesize proteins necessary for survival and growth.