The relationship between bacteriophage and host polymerase for the transcription of its own gene

Since this process is very complex, I will simplify this mechanism

- Normally, bacteriophage does not encode its own RNA pol, so it must rely on the host RNA pol to transcribe its gene.

- Transcription from early bacteriophage promoter is initiated by the host holoenzyme containing the host sigma factor.

- There will be a competition for host sigma factor to bind with between bacteriophage promoter and host promoter. In this case, if bacteriophage wants host holoenzyme binds it promoter, it must make sure that its promoter must be strong ( meaning that it must have high affinity for host holoenzyme).

- When this process is accomplished, this transcription produces viral sigma factor. This viral sigma factor will steal RNA pol from host to synthesize its own gene and a new sigma factor ( let just denote as sigma *.

- The second sigma factor ( sigma*) will again bind to host RNA pol for its transcription to generate other part of viral structure like capsid.

- Note: always, there will be a competition for the binding of host holoenzyme between viral promoters and host promoter, as well as viral sigma factor with the new viral sigma factor*. This process totally is dependent on affinity of the molecular interactions.