Stringent response_Pwt

stringent response

A cellular response to idle ribosomes (often indicating low carbon and energy stores) that includes a decrease in rRNA and tRNA production. a regulatory mechanism that detects nutrient or environmental stresses and antibiotics a global regulatory control that is activated by amino acid starvation or energy deficiency

stringent response in E. coli

A decrease in tRNA, rRNA & an increase in specific amino acid biosynthetic enzymes in response to amino acid starvation

The stringent response: an E. coli-centric view SLIDE NOTES: It's true of all organisms that starvation inhibits growth. In e. coli one of the most important ways this cessation of growth is regulated is via the stringent response. In the stringent response the small molecule ppGpp, or magic spot, is synthesized upon starvation. This molecule binds directly to RNAP and affects is affinity for different promoters, causing a large-scale transcriiptional reprogramming of the cell. magic spot is synthesized by the enzymes RelA and SpoT in E. coli. RelA responds only to amino acid starvation. This enzyme is bound to the ribosome and it senses amino acid starvation by detecting an uncharged tRNA in the a site of the ribosome. SpoT detects sugar, ammonia, lipid, iron, phosphate and amino acid starvation. It is not know whether SpoT binds the ribosome or how it is regulated.

The stringent response: an E. coli-centric view