Research Diary

Operon: A unit of genetic material that functions in a coordinated manner by means of an operator, a promoter, and one or more structural genes that are transcribed together.

Sigma Factor: A sigma factor (σ factor) is a prokaryotic transcription initiation factor that must be part of RNA polymerase (RNAP) for specific binding to promoter sites on DNA. Different sigma factors are activated in response to different environmental conditions, as are listed below. Every molecule of RNA polymerase contains exactly one sigma factor subunit, which in the model bacterium Escherichia coli is one of those listed below. E.coli has at least eight sigma factors; the number of sigma factors varies between bacterial species. All sigma factors are distinguished by their characteristic molecular weights. For example, σ70 refers to the sigma factor with a molecular weight of 70 kDa.