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In genetics, a transcription terminator is a section of nucleic acid sequence that marks the end of a gene or operon in genomic DNA during transcription.This sequence mediates transcriptional termination by providing signals in the newly synthesized transcript RNA that trigger processes which release the transcript RNA from the transcriptional complex.
Overview of transcription process. Termination of transcription occurs due to termination signal. In molecular biology, a termination signal is a sequence that signals the end of transcription or translation. [1] Termination signals are found at the end of the part of the chromosome being transcribed during transcription of mRNA.
The process of termination by Rho factor is regulated by attenuation and antitermination mechanisms, competing with elongation factors for overlapping utilization sites (ruts and nuts), and depends on how fast Rho can move during the transcription to catch up with the RNA polymerase and activate the termination process. [7]
Termination of transcription occurs in the ribosomal intergenic spacer region that contains several transcription termination sites upstream of a Pol I pausing site. Through a yet unknown mechanism, the 3’-end of the transcript is cleaved, generating a large primary rRNA molecule that is further processed into the mature 18S, 5.8S and 28S rRNAs.
Intrinsic, or rho-independent termination, is a process to signal the end of transcription and release the newly constructed RNA molecule. In bacteria such as E. coli , transcription is terminated either by a rho-dependent process or rho-independent process.
Transcription termination in eukaryotes is less well understood than in bacteria, but involves cleavage of the new transcript followed by template-independent addition of adenines at its new 3' end, in a process called polyadenylation. [49]
Rho-dependent termination: ρ factor (rho factor) is a terminator protein that attaches to the RNA strand and follows behind the polymerase during elongation. [5] Once the polymerase nears the end of the gene it is transcribing, it encounters a series of G nucleotides which causes it to stall. [ 1 ]
Termination requires that the progress of the DNA replication fork must stop or be blocked. Termination at a specific locus, when it occurs, involves the interaction between two components: (1) a termination site sequence in the DNA, and (2) a protein which binds to this sequence to physically stop DNA replication.