σ factor
Definition
σ factor is a protein needed for the initiation of transcription in bacteria. It enables RNA polymerase to bind to specific promoter regions on DNA.
5 Must Know Facts For Your Next Test
- σ factor helps RNA polymerase recognize and bind to promoters.
- Different σ factors recognize different sets of promoters, allowing for differential gene expression.
- The primary σ factor in E. coli is σ70, which recognizes most housekeeping genes' promoters.
- Alternative σ factors are used during specific conditions, such as heat shock or nitrogen starvation.
- σ factors dissociate from RNA polymerase after the initiation of transcription, allowing elongation to proceed.
Review Questions
- What role does the σ factor play in bacterial transcription?
- How do alternative σ factors contribute to gene regulation?
- Why does the σ factor dissociate from RNA polymerase after transcription initiation?
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Related terms
RNA Polymerase: An enzyme that synthesizes RNA from a DNA template.
Promoter: A DNA sequence that initiates gene transcription by providing a binding site for RNA polymerase and associated proteins like the σ factor.
Operon: A cluster of genes under the control of a single promoter, transcribed into a single mRNA molecule.
