1. RNA polymerase: This is the primary enzyme responsible for transcription. It binds to the DNA template and unwinds it, then uses the template strand to synthesize a complementary RNA molecule.

2. DNA helicase: This enzyme unwinds the DNA double helix to expose the template strand.

3. Topoisomerase: This enzyme relieves the torsional stress that builds up in the DNA as it is unwound by helicase.

While these three are the most essential, other enzymes might be involved in specific processes, such as those assisting in initiation and termination of transcription.