Termination

Bacteria using a strategy for the termination of transcription of two different – Rho-dependent end of the end of the independence of Rho. The RNA molecules that are newly synthesized, the transcription termination that does not Rho dependent called Exit essential, RNA transcription stops even when Following our series, thereby forming a hairpin loop GC-rich You. Acute form of mechanical stress If you failed, the binding RU-DA weak filling the DNA-RNA hybrid current. I pull the poly-U copy of the active center of the RNA polymerase in the sense that terminates transcription. In suspension called “low” “low dependent” type, the protein factor, release was synthesized from elongation complex of mRNA newly in this manner, non-interaction between the mRNA template and to stabilize. When you exit the transcription of eukaryotic organisms, it is small, but of course, in a process called polyadenylation, in addition template independence to a new 3 ‘end, are included, the cutting of new entry followed.

It is a mechanism in prokaryotes that causes the RNA transcription (referred not to Rho-dependent termination also) internal termination is stopped. In this mechanism, mRNA is cytosine – Includes an array can be calculated in a pair with itself to form a stem-loop structure 7-20 base pairs in length guanine base pair is rich. These bases, so to form three hydrogen bonds with each other, very strong. I have a chain of uracil residues after the stem-loop structure. Link between the uracil and adenine is very weak. Polymerase closely enough to bind to stem loop structure To be thrown down temporarily proteins associated with RNA polymerase (Nusa Dua). This break, poly – are consistent with transcription polymerase sequence of uracil. Uracil bonds – weak adenine can be dissociated to relax from the RNA polymerase, lowering the energy of the destabilization of the double-stranded RNA-DNA.

Will cause the RNA polymerase to stem-loop structure that do not comply by poly uracil sequence will pause, but so is stable too to fully relax to cause an end to the double, usually, it after a short time, I will continue to transcription.
In many cases, ρ-independent transcription termination mechanism is the basis of the activity of the RNA cis-acting regulatory elements, as riboswitch.

E. coli genome equencing whole may have a termination sites most of the operon is not dependent on the row are shown. In the transcribed RNA, a series of U residues in front of those of self-complementary region a GC-rich and nucleotides intervening some: I have two characteristics in extreme sequence of these. Area of ​​the self-growth of additional RNA strand are synthesized with each other to form a stem-loop structure, base pairs of additional sequences. The stem-loop structure is believed to interact with the recording of E. coli RNA polymerase and cause it to break. Further, base pairs between the residues in the template DNA strand U and Watson 3 ‘end of the residual nascent RNA chain – very unstable as compared to other types of Crick base pairs. These two features, have solved the release of the RNA strand of the transcription complex at the end sites that do not depend on Rho probably. Mutations that decrease and results dyad symmetry to U, a continuous low end to reduce the part of these sites.

Several mechanisms for the regulation of transcription is found in eukaryotes and bacteria. RNA polymerase plays a role of two primary mechanisms for the conclusion of the occurrence transcription in E. coli. Additional proteins, called rows, transcription terminators, a mechanism is required, but not the other. In many cases, these mechanisms are referred to as dependent end of Rho If you do not depend on low. In eukaryotes, the mechanism of transcription termination seems to be different in each RNA polymerase three. Here, I focus on the end of the first mechanism in bacteria that will be understood from the mechanisms of eukaryotic organisms has been described by way of example research well two of termination of transcription of eukaryotic more clearly.

Another mechanism for the regulation of gene expression in bacteria, called recognized by the analysis of a particular strain of E. coli mutant first tryptophan operon is attenuated. In the presence of tryptophan, tryptophan repressor, please recall that to inhibit the transcription of TRP operon. However, it is not exhaustive, according to protein synthesis, this inhibition is complemented by the weight loss to provide the level of regulation of tryptophan synthesis.

In essence, attenuation results in early termination of transcription at the attenuator site located downstream of the coding sequence of the enzyme TRP and before, from the operator region – promoter. The presence of E. coli, the tryptophan and mutant with a small deletion in the area of ​​manufacturing tryptophan operon more than the normal amount of tryptophan synthase in the absence. Trp mRNA of the Trp promoter nearby sequence comparison of researchers at the start of the RNA molecule, deletions and these, or may lead to increased synthesis of DNA region of Trp in both mutant and normal E. mRNA molecules of normal, contains 162 nucleotides upstream of Trp August the first initiation codon of the enzyme that is encoded TRP-five in order to understand. This part of the mRNA are referred to as (L) leader sequence. MRNA transcript tryptophan rich TRP only and will not be transferred consists of the rest of the 7 KB TRP operon ≈ and only leader RNA by virtue of the action of the tryptophan repressor of E. coli cells normal production the transcription of these. When tryptophan is limited, however, comprises a coding sequence for all of the enzyme is encoded trp promoter and leader sequence, tryptophan operon is transferred as a whole. normal cells than do mutant cells is the attenuation region has been deleted, to produce a mRNA of Trp twist in all conditions.