An E3 ubiquitin ligase binds to Phosphoserines of I-κBα & links poly-K48-linked ubiquitin chains that target the attached I-κBα protein to the proteasomal degradation

TLS Online TPP Program

#Id: 6315

#Unit 3. Fundamental Processes

Model of Intrinsic Termination

Bacterial terminators act by:

TLS Online TPP Program

#Id: 6316

#Unit 3. Fundamental Processes

Readthrough transcripts refer to the fraction of transcripts that are not stopped by the terminator.  Furthermore, the termination event can be prevented by specific ancillary factors that interact with RNA and/or RNA polymerase, a situation referred to as antitermination.

TLS Online TPP Program

#Id: 6317

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6318

#Unit 3. Fundamental Processes

Rho binds to a sequence within the transcript upstream of the site of termination. This sequence is called a rut site (an acronym for rho utilization). 

The rho factor then tracks along the RNA until it catches up to RNA polymerase. When the RNA polymerase reaches the termination site, rho first freezes the structure of the polymerase and then invades the exit channel to destabilize the enzyme, causing it to release the RNA.

TLS Online TPP Program

#Id: 6319

#Unit 3. Fundamental Processes

A rut site has a sequence rich in C and poor in G preceding the actual site(s) of termination. The sequence corresponds to the 3’ end of the RNA.

TLS Online TPP Program

#Id: 6320

#Unit 3. Fundamental Processes

Rho is a member of the family of hexameric ATP-dependent helicases. Each subunit has an RNA-binding domain and an ATP hydrolysis domain.