Post Transcriptional Regulation Flashcards
transcriptional attenutation
-regulation that involves terminating mRNA syntheis before genes are trasncribed
can stability of mRNAs be controlled
-yes,
can translation efficiency be controlled
yes, through whether or not RBS is free to be bound by ribosome
mRNA lifetimes
-bcterial transcrupts do not last long
-all cells contain multiple ribonucleases
-different mRNAs can have very different half lives
-why some mRNA are targeted more/less by RNAses is complex and often unclear
-Regulatory proteins/RNAs can bind to mRNA and impact its half life
transcuptional attenuation
during transcription the formation of rho-independent trasncriptional terminators before a genes transcription is complete leads to transcriptional attenuation
RNA structure that shut off gene expression
formation of stem loop structures in mRNA can shut off gene expression if they involve RBS, oe involve the formation of a transcriptional terminator upstream of a gene, these can be regulated
sRNA
-50-30 nt long
-geneerally exert effects by base pairing to target mRNAs
-base paring with sRNA affects how RBS avaliability and or Rnase targeting therefore controlling how much proteins gets madde
riboswitches
-ligand binding RNAs
-bind sparticular molecule
-binding allows riboswithxes to sense their environments
-Reside in 5’UTR of certain bacterial mRNAs
-regulate downstream genes on same mRNA
-ligand binding changes RNA structure in 5’UTR this change induces or represses expression of downstream genes
-found in all 3 domains
-very different from sRNAs
riboswitch mechanisms
-RNA domain called aptamer binds ligand
-binding changes base paring in the 5’UTR of mRNA to affect formation of either stem loop thats equesters RBS or transcriptional terminator that prevents transcription of the gens
riboswitch history
-riboswitches have been hypotheiszed to be relics from the RNA world
-riboswitches bind a wide range of metabolites
-structurally conserved aptamer domains in divergent lineages
-binding of such metabolites would have been essential in RNA world in order to sense the environment
post translation regulation
feedback inhibition: enzyme of biosynthetic pathway is sometimes inhibited by the end product of that pathway
-activity of proteins can also be regulated by protein-protein interactions
-protein activity can be changed via post tranlational modifications (eg. adding phophate group)
protein degredation
-proteases
-proteases essential for cleearing away recycling and misfolded proteins
-in other cases proteolysis can be bery specific and regulated mechanism to clear away specific proteins in the cell
-some proteins requrie proteolytic activity to be activated
