What do sigma factors do?

Sigma factors are subunits of all bacterial RNA polymerases. They are responsible for determining the specificity of promoter DNA binding and control how efficiently RNA synthesis (transcription) is initiated.

What is Extracytoplasmic?

(biology) From outside of the cytoplasm of a cell.

What is sigma factor a component of?

Members of the sigma70 family of sigma factors are components of the RNA polymerase holoenzyme that direct bacterial or plastid core RNA polymerase to specific promoter elements that are situated 10 and 35 base-pairs upstream of transcription-initiation points.

How do sigma factors regulate gene expression?

Sigma factors act by binding to and influencing the promoter specificity of the RNA polymerase core enzyme, thereby directing selective transcription of different gene sets, coordinating gene expression in response to various environmental and endogenous cues.

What do you mean by transcription factors?

Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.

What is an alternative sigma factor?

Alternative Sigma Factors. Sigma factors act by binding to and influencing the promoter specificity of the RNA polymerase core enzyme, thereby directing selective transcription of different gene sets, coordinating gene expression in response to various environmental and endogenous cues.

What is the function of Rho factor?

Rho factor attaches to the mRNA transcript and uses its helicase function to track along the transcript toward the moving mRNA polymerase [2]. Upon catch- ing up with the polymerase, Rho catalyzes the disasso- ciation of mRNA from genomic DNA and the RNA polymerase [2].

What is meant by Rho factor?

The Rho factor is a protein that acts in bacterial cells to mediate termination of transcription at distinct sites. Escherichia coli, and probably most bacteria, have two sets of transcriptional terminators: intrinsic and Rho-dependent.

Why sigma factor is released?

However, particularly common among alternative σ factors is their control by specific anti-σ proteins that impede RNAP binding. The σ factor is then released in response to a signal that is perceived either by the anti-sigma factor itself or by additional components in more complex signal-relay type systems.

What is the role of sigma factor in prokaryotic transcription?

Sigma factors (sigmas) are bacterial transcription factors that bind core RNA polymerase (RNAP) and direct transcription initiation at cognate promoter sites.