Role
of
RNA
Polymerases - The sigma factor interacts with the core enzyme to form the complete enzyme. The β subunit of the core enzyme is required for interaction with the sigma factor. The core enzyme by itself is ineffective in transcribing RNA, because it transcribes both strands.
The holozyme on the other hand transcribes only one strand of the DNA template (asymmetrical transcription). The sigma factor recognizes the start signal on DNA and directs the binding of the enzyme to the promoter region. It thus enhances the specificity of transcription. The binding of RNA polymerase to DNA involves the β ' subunit.
