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Riboswitch-controlled formation of rho-independent transcription termination hairpins leads to premature transcription termination. Riboswitch-mediated folding sequesters the ribosome-binding site, thereby inhibiting translation. The riboswitch is a ribozyme that cleaves itself in the presence of sufficient concentrations of its metabolite.
The TPP riboswitch, also known as the THI element and Thi-box riboswitch, is a highly conserved RNA secondary structure. It serves as a riboswitch [1][2] that binds thiamine pyrophosphate (TPP) directly and modulates gene expression through a variety of mechanisms in archaea, bacteria and eukaryotes. [3][4][5] TPP is the active form of thiamine ...
Glycine riboswitch. The bacterial glycine riboswitch is an RNA element that can bind the amino acid glycine. Glycine riboswitches usually consist of two metabolite-binding aptamer domains with similar structures in tandem. The aptamers were originally thought to cooperatively bind glycine to regulate the expression of downstream genes.
Histone acetylation and deacetylation. The crystal structure of the nucleosome core particle consisting of H2A , H2B , H3 and H4 core histones, and DNA. The view is from the top through the superhelical axis. Histone acetylation and deacetylation are the processes by which the lysine residues within the N-terminal tail protruding from the ...
Attenuator (genetics) In genetics, attenuation is a regulatory mechanism for some bacterial operons that results in premature termination of transcription. The canonical example of attenuation used in many introductory genetics textbooks, [ 1 ] is ribosome-mediated attenuation of the trp operon. Ribosome-mediated attenuation of the trp operon ...
A typical operon. In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. [1] The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product.
The riboswitch functions by directly sensing a physiological signal. [10] Next, a specific uncharged tRNA binds to a riboswitch element in the transcript, and a structural change occurs in the transcript that promotes expression of the downstream coding sequence. [2] [10] The specifier sequence is the first recognition sequence in the leader. [7]
Ribozyme. 3D structure of a hammerhead ribozyme. Ribozymes (ribo nucleic acid en zyme s) are RNA molecules that have the ability to catalyze specific biochemical reactions, including RNA splicing in gene expression, similar to the action of protein enzymes. The 1982 discovery of ribozymes demonstrated that RNA can be both genetic material (like ...