MICRB316 Lecture Notes - Lecture 4: Sigma Factor, Streptomyces Coelicolor, Exponential Growth
8 Mar 2014
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Document Summary
They direct rnap to initiate transcription at specific promoters to allow differential expression of a particular subset of genes. First described for bacillus subtilis & phages sp01/sp82. And a common feature in all bacteria e. g. e. coli 7 factors. The specificity of rnap for promoter sequences can be modified by different s specific for their own promoter sequences. Others have promoter specificities that overlap with other sigma factors. factors. Phage have different sigma factors for different life stages. Sigma s is similar to sigma 70 and used for stationary phase expression. Sigma factors have evolutionary tree that is devided into groups. The different conditions that the bacteria can live under. Changes in life cycle: what does it help with, genitalium: smallest genome. One sigma factor: coelicolor: soil bacteria with large genome. Regulation: concentration a. synthesis, protein stability, activity modulated by modification, cleavage of protein sequence, interaction with inhibitors (anti sigma factors)
