Biology – Principles of genetic technology | e-Consult

Inserting a human gene into a plasmid alone will likely not result in the desired protein being produced in *E. coli* because *E. coli* lacks the necessary regulatory elements to initiate transcription of a human gene. The human gene contains sequences that are specific to eukaryotic transcription machinery, which are different from the prokaryotic machinery found in *E. coli*.

The promoter overcomes this issue by providing a sequence recognized by the *E. coli* RNA polymerase. The *E. coli* promoter will direct the RNA polymerase to bind to the plasmid DNA and initiate transcription of the human gene. This allows the *E. coli* cell to transcribe the human gene into mRNA, which is then translated into the human protein.

The promoter essentially bridges the gap between the human gene (which has eukaryotic regulatory sequences) and the *E. coli* cellular machinery (which has prokaryotic regulatory sequences). Without the promoter, the *E. coli* cell would not be able to recognize the human gene as a target for transcription, and the gene would remain silent. The promoter ensures that the human gene is transcribed and translated within the *E. coli* cell, allowing for protein production.