On the one hand, this type of organizational structure benefits from having individuals entirely dedicated to one function. In some cases, there can be cost savings and efficiency gains in combining functions in this way. However, this type of organizational structure is prone to conflict.
The alpha subunit (RpoA) initiates RNAP assembly by dimerising to form a platform on which the beta subunits can interact. The alpha subunit consists of a N-terminal domain (NTD) and a C-terminal domain (CTD), connected by a short linker.
In bacteria, all transcription is performed by a single type of RNA polymerase. This polymerase contains four catalytic subunits and a single regulatory subunit known as sigma (s). Interestingly, several distinct sigma factors have been identified, and each of these oversees transcription of a unique set of genes.