Together, these mechanisms are known as attenuation and antitermination, and both involve controlling the formation of a transcription. Some antitermination factors allow bypass of a single terminator in response to a . Attenuation through ribosome positioning, Leader RNA, Typical of amino. This mechanism is very similar to attenuation, but antitermination can be distinguished RNA-Binding Protein-Mediated Antitermination: The Sac/Bgl Family of.

Author: Kajilrajas Tut
Country: Togo
Language: English (Spanish)
Genre: Art
Published (Last): 7 June 2005
Pages: 392
PDF File Size: 16.59 Mb
ePub File Size: 10.52 Mb
ISBN: 962-6-19407-941-7
Downloads: 19089
Price: Free* [*Free Regsitration Required]
Uploader: Tojar

Termination and antitermination: RNA polymerase runs a stop sign

Kaczanowska M, Ryden-Aulin M. The role of other Nus factors in rrn regulation in vivo is not clear.

The tRNA is antiterrmination as the shaded cloverleaf structure, and a boxed “A. Artsimovitch I, Landick R. Given that the structural and functional organization of all cellular RNAPs is remarkably conserved 9lessons learned from attenuatlon have been, and will probably be in the future, applicable to higher organisms.

The T box mechanism: We examine attenuation and antitermination from the point of view of the different biomolecules that are used to influence the RNA structure.

There was a problem providing the content you requested

Antitermination also appears to control b-glucoside operons in several Gram-Positive Bacteria as well. In addition, cellular znd should permit RNAP release at the end of an operon, and most of the intergenic terminators are intrinsic The larger class comprises proteins, RNAs and small molecules that act on a terminator.

The recognition sites required for pN action are called nut for N utilization. It was the presence of these triplets that led to the hypothesis that tRNAs play a role in this regulatory mechanism.

It is not known whether the N-containing antiterminator complex actively inhibits Rho by blocking its access to RNA 79 or simply speeds up the RNAP, allowing it to escape from the advancing Rho. Peters JM, et al. Processive antitermination can be mediated by RNA as well as proteins. The host RNA polymerase initially transcribes two genes, which are called the immediate early genes N and cro.


Other signals are simply roadblocks that the enzyme must bypass to complete synthesis of an RNA chain; for example, sequences that favour backtracking and arrest 7 or proteins that are bound to DNA 8 hinder RNAP movement.

In addition, transcription can be regulated at the level of elongation. Thus, antiterminaiton tethered ribosome may function as an antiterminator by preventing Rho binding to mRNA, inhibiting Rho-mediated RNA release by sequestering the Rho-interaction surface on NusG, and blocking formation of a terminator hairpin.

Two classes of regulators help RNAP to read through terminators. Ribosome biogenesis and the translation process in Escherichia coli. Passive, site-specific antiterminators encoded by phages. When Trp levels are low, the ribosome stalls at one of two Trp codons at positions 10 and 11 within the leader peptidethe antiterminator hairpin forms and Trp biosynthesis genes are expressed, leading to an increase in the concentration of Trp.

Transcription attenuation.

Ruiz and the anonymous referees for their help in improving the manuscript. By using this site, you agree to the Terms of Use and Privacy Policy.

In the first case, the action of the termination signal itself is compromised for example, by the antiterminator preventing the formation of the RNA hairpin or the action of Rhobut RNAP is unaltered. Curr Opin Struct Biol.

If glucose is present, the phosphate groups are transferred from PtsG to the sugar instead. Richardson J, Greenblatt J. A HutP hexamer binds to an untranslated RNA region that separates the hutP gene from the downstream genes encoding enzymes which degrade His. The target sites for the antitermination factors are shown as transparent ovals.

In NusG, the C-terminal domain interacts with Rho to increase Rho-dependent termination 9394 and with the ribosomal protein S10 to couple transcription to translation 69 Termination can be controlled with the same sort of precision as initiation.


Cardinale CJ, et al. An allosteric path to transcription termination. RNA sequence requirements for NasR-mediated, nitrate-responsive transcription antitermination of the Klebsiella oxytoca M5al nasF operon leader. A bacterial mRNA leader that employs different mechanisms to sense disparate intracellular signals. The antitermination protein produced at each stage is specific for the particular transcription units that are expressed at that stage.

Transcription against an applied force.

Termination and antitermination: RNA polymerase runs a stop sign

A conserved zinc binding domain in the largest subunit of DNA-dependent RNA polymerase modulates intrinsic transcription termination anc antitermination but does not stabilize the elongation complex. Structural mechanism of signal transduction between the RNA-binding domain and the phosphotransferase system regulation domain of the LicT antiterminator.

From Wikipedia, the free encyclopedia. It is believed that this accounts for the phage specificity of N-mediated antitermination.

The role of NusG in the N antitermination reaction is not clear. The first is the result of interaction between lambda N protein and its targets in the early phage transcripts, and the second is the result of an interaction between the lambda Q protein and its target in the late phage promoter. Phage HK attenuationn L and t R.

Mutagenesis-based evidence for an asymmetric configuration of the ring-shaped transcription termination factor Rho. RNA polymerase interacts with transcription units in such a way that an ancillary factor can sponsor antitermination specifically for some transcripts.

It stimulates the rate of transcription elongation and attneuation required for the activity of certain Rho-dependent terminators. These regulatory systems thus appear to ajtitermination arisen independently. Translation activates the paused transcription complex and restores transcription of the trp operon leader region. In attenuation, the action of the regulatory molecule induces transcription termination, and the default pathway is readthrough.