The proteins that bind to DNA and turn on operons by making it easier for RNA polymerase to bind to a promoter are called activator proteins.

Here's a breakdown:

* Operon: A group of genes that are transcribed together as a single unit.

* Promoter: A DNA sequence where RNA polymerase binds to initiate transcription.

* Activator protein: A protein that binds to a specific DNA sequence (often called an activator binding site) near the promoter, which enhances the binding of RNA polymerase to the promoter and increases the rate of transcription.

These proteins are crucial for regulating gene expression by controlling the accessibility of the promoter to RNA polymerase.