riboswitches and translational control

what is thermosensory regulation?

RNA thermosensors are able to sense a change in temperature, allowing SD exposure and translation

* basically, secondary structures melt at high temps
* rpoH gene encodes for sigma H factor
* activates DnaK, DnaJ, and GrpE

Which sigma factor is found in most genes?

sigma 70 promoter

What is a riboswitch?

a riboswitch is an RNA element found in the leader sequence that controls for the coding sequence

What does a riboswitch do?

Riboswitches form 3D structures that bind to small ions. This controls the production of the protein encoded by that mRNA

What types of riboswitches are there?

* riboswitch controlled formation of rho-independent transcription termination hairpins
* riboswitch mediated folding inhibiting ribosome binding
* riboswitch ribozymes that cleave themselves
* riboswtich alternate structure

what was the first riboswitch discovered?

amino acyl tRNA synthetase

What happens if there are high levels of uncharged tRNAs?

A hairpin in the specifier loop will end transcription and induce production of amino acyl synthetases to create aa-tRNA

What are metabolite binding riboswitches?

metabolite binding riboswitches bind small molecules to induce a conformational change and block transcription and translation

What are riboflavin riboswitches?

riboflavin riboswitches regulate the riboflavin operon

* when FMN is present, operon is repressed
* FMN will bind into the RFN structure and create a terminator loop

What is a thiamine riboswitch?

a thiamine riboswitch sequesters SD sequence, and blocks translation initiation

* binds thiamine and pyrophosphate

What is a regulon?

genes or operons controlled by a common regulatory protein

What is known as the master regulator?

guanosine tetraphosphate

What is the stringent response?

the stringent response is where translation stalls if it cannot find enough associated codons

* saves cellular resources
* its being stingy lol

What occurs when the stringent response occurs?

* guanosine tetraphosphate forms (ppGpp) via RelA and binds to the ribosome in place of tRNA
* creates alarmone as it starves