“Replicon” is usually applied to eukaryotic chromosomes to describe a unit of replication that contains an origin; trans-acting regulator protein

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.

TLS Online TPP Program

#Id: 6321

#Unit 3. Fundamental Processes

After binding to the rut site, rho uses its helicase activity, driven by ATP hydrolysis, to translocate along RNA until it reaches the RNA polymerase

TLS Online TPP Program

#Id: 6322

#Unit 3. Fundamental Processes

Nonsense mutation in one gene of a transcription unit was found to prevent the expression of subsequent genes in the unit even though both genes had their own ribosome binding sites, an effect called polarity.

TLS Online TPP Program

#Id: 6323

#Unit 3. Fundamental Processes

Rho-dependent termination sites within a transcription unit are usually masked by translating ribosomes and therefore rho cannot act on downstream RNA polymerases

TLS Online TPP Program

#Id: 6324

#Unit 3. Fundamental Processes

Nonsense mutations release ribosomes within the RNA of a multigene operon, though, enabling rho to terminate transcription prematurely and prevent expression of distal genes in the transcription unit even though their open reading frames contained wild-type sequences.