Introduction to Bacterial Gene Regulation Lecture

Riboswitches are sensory RNA molecules that fold in response to metabolites or other effectors, influencing mRNA transcription continuation, half-life, and translation.

Sigma factors are involved in recognizing promoters and enhancing specificity in transcription, thereby regulating gene expression.

Post-transcriptional control involves mechanisms like riboswitches, regulation of mRNA stability, and occlusion of the Shine Dalgarno site to modulate translation.

tRNAs, like in the T box system, can impact the expression of specific genes, such as tyrosyl tRNA synthetase in Gram-positive bacteria.

Hierarchical control mechanisms help coordinate different levels of gene expression regulation, ensuring precise responses to environmental cues.

Riboswitches fold in response to specific metabolites or effectors, altering their structure to modulate gene expression.

The Shine Dalgarno sequence serves as a ribosomal binding site, facilitating the initiation of translation of mRNA into protein.

Bacteria employ the SOS response as a global response to sudden global DNA damage, which involves the expression of a subset of proteins to permit the bacterium to survive current conditions.

Sigma factors bind to RNA polymerase and help determine the promoter recognition specificity of the enzyme, leading to the transcription of specific genes.

The lac operon allows bacteria to utilize lactose as an energy source. The operon is regulated by the lac repressor protein, which binds to the operator site and prevents the transcription of the lac genes in the absence of lactose.

The 5' UTR contains important regulatory elements such as the Shine Dalgarno sequence, while the 3' UTR plays a role in mRNA stability and localization.

Mechanisms for controlling protein function in bacteria include post-translational modifications, allostery, and protein-protein interactions.

It acts as a thermostat and signal for degradation, preventing translation at normal temperatures and allowing translation during heat shock.

RpoH is released from the chaperone, allowing it to associate with RNA polymerase and increase transcription from RpoH-dependent promoters.

RpoH levels decline in the cytoplasm, reducing the amount of sigma factor binding RNA polymerase, and thus decreasing transcription from RpoH-dependent promoters.

The three different types of regulatory control are transcriptional, post-transcriptional, and post-translational. Transcriptional control involves regulation at the level of transcription, post-transcriptional control involves regulation at the level of RNA processing and stability, and post-translational control involves regulation at the level of protein activity and stability.

ClpB is a foldase that re-folds proteins to their correct conformation, helping to restore normal function.

RpoH associates with RNA polymerase, increasing transcription from RpoH-dependent promoters, leading to the expression of heat shock genes.

Sigma factors are proteins that bind to the RNA polymerase core enzyme and direct it to recognize specific promoter sequences on DNA. They play a crucial role in transcription initiation by helping to recruit RNA polymerase to the promoter and unwind the DNA double helix.

Riboswitches are RNA molecules that can bind specific metabolites or other small molecules to change their conformation, thereby regulating gene expression. They contribute to post-transcriptional regulation by controlling mRNA processing, stability, or translation.

It only allows for rapid responses to short exposures to heat shock, but is not effective for prolonged heat stress or in the periplasm.

RpoH and RpoE are both heat shock transcription factors that are tightly regulated at the post-translational level. RpoH is degraded by the protease FtsH, which is inhibited at high temperatures, allowing for increased RpoH activity. RpoE is regulated by a feedback loop involving its own gene and the protease DegS, which senses misfolded outer membrane proteins and activates RpoE in response.

An operon is a group of genes that are coordinately regulated by a single promoter, while a regulon is a group of genes that are regulated by a common set of factors, which may be located in different regions of the genome.

The central dogma of molecular biology outlines the flow of genetic information from DNA to RNA to protein, which is the basis for understanding the different levels of gene regulation in bacteria. By understanding the central dogma, we can better understand how gene expression is controlled at each stage of the process.

Normal growth conditions, where Sigma E is sequestered by RseA and RseB, and RpoE associates with RNA polymerase only at low levels.

DegS unfolds and becomes active during stress, degrading misfolded proteins, and releasing RpoE from RseA and RseB.

RpoE associates with RNA polymerase, inducing the stress response, which includes the expression of RpoH.

RpoE re-associates with RseAB, shutting off the response.

YaeL protease releases RpoE from RseA and RseB.

The increased mRNA from RpoH will unwind and be translated.