Riboswitch
FunctionNormally, a variety of proteins and protein cofactors control gene expression in an organism by binding to different sites on messenger RNA (mRNA). Riboswitches are genetic regulatory elements that are built directly into the RNA. They are a type of noncoding RNA that regulate gene expression in the absence of proteins by switching from one structural conformation (shape) to another in response to ligand binding. Most contain a single binding site that recognizes a specific ligand. The ability of a riboswitch to discriminate against molecules that are similar or closely related to its ligand is essential to prevent metabolic misregulation[1]. The various classes of riboswitches discovered so far are differentiated by their respective ligands. Every class of riboswitch is characterized by an aptamer (binding site) domain, which provides the site for ligand binding, and an expression platform that undergoes conformational change. The sequences and structures of aptamer domains are highly conserved, and therefore exhibit little variation among riboswitches belonging to the same class. For details on guanine riboswitch see Structural highlightsAtomic-resolution structures of riboswitch binding sites show that they make numerous hydrogen bonds with their ligands, forming contacts that stabilize RNA interactions to further increase affinity. Some binding sites form pockets that entirely engulf the ligand, and in these instances an induced-fit mechanism of binding must occur. The riboswitch-adenine complex shows the stacking interactions of the zippered-up junctional bubble which is formed by the adenine[2]. Water molecules shown as red spheres.
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3D structures of riboswitch
Updated on 14-September-2018
- Adenine riboswitch
- Guanine-Binding Riboswitch, Guanine riboswitch, 4tzy, 4xnr, 5swd, 5swe, 5uza – VvAR + adenine – Vibrio vulnificus
- 5e54 – VvAR
- 3ivn – BsAR (mutant) – Bacillus subtilis
- 3la5 - BsAR (mutant) + azacytosine
- Guanine-Binding Riboswitch, Guanine riboswitch, 4tzy, 4xnr, 5swd, 5swe, 5uza – VvAR + adenine – Vibrio vulnificus
- Guanine riboswitch
- 1y27 – BsGR residues 185-252 + guanine
- 2g9c, 3fo4, 3fo6, 3ges, 3gog, 3rkf - BsGR (mutant) + guanine derivative
- 3got - BsGR (mutant) + adenine derivative
- 2xo1 - BsGR aptamer domain + adenine derivative
- 3g4m, 3ger - BsGR + guanine derivative
- 2xnz - BsGR aptamer domain + guanine derivative
- 2xo0 - BsGR aptamer domain + triazine derivative
- 5c7u, 5c7w - BsGR + hypoxanthine
- 2ees, 2eet, 2eeu, 2eev, 2eew - BsGR (mutant) + hypoxanthine
- 3gao - BsGR + xanthine
- 2xnw – BsGR + Mn
- 4fe5, 4fej, 4fel, 4fen, 4feo, 4fep – GR + hypoxanthine – synthetic
- 1y27 – BsGR residues 185-252 + guanine
- Thiamine pyrophosphate riboswitch
- 2gdi – TPPR + TPP – synthetic
- 2hoj, 2hok, 2hol – EcTPPR + TPP + metal ion – Escherichia coli
- 2hom – EcTPPR + TMP
- 2hoo, 2hop – EcTPPR + TPP analog
- 4nya, 4nyb, 4nyc – EcTPPR + pyrimidine derivative
- 4nyd – EcTPPR + hypoxanthine
- 4nyg – EcTPPR + thyamine
- 3d2g, 3d2v, 3d2x - TPPR + TPP analog – Arabidopsis thaliana
- 2gdi – TPPR + TPP – synthetic
- S-adenosylmethionine riboswitch
- 2gis, 4aob, 4b5r – TtSAMR + SAM – Thermoanaerobacter tengcongensis
- 3iqr, 2ydh, 2ygh - TtSAMR (mutant) + SAM
- 3iqp - TtSAMR
- 5fjc, 5fk1, 5fk2, 5fk3, 5fk4, 5fk5, 5fk6, 5fkd, 5fke, 5fkf, 5fkg, 5fkh - TtSAMR + SAM + GTP
- 2qwy, 3e5c, 3e5e, 3e5f, 3iqn - SAMR + SAM – synthetic
- 4kqy – BsSAMR + SAM
- 4oqu - SAMR + SAM - synthetic
- 2gis, 4aob, 4b5r – TtSAMR + SAM – Thermoanaerobacter tengcongensis
- S-adenosylhomocysteine riboswitch
- Lysine riboswitch
- Glutamine riboswitch
- FMN riboswitch
- Pre-queosine riboswitch
- C-di-GMP riboswitch
- 3irw, 3mxh – VcGMPR + C-di-GMP + GTP + U1 small nuclear ribonucleoprotein – Vibrio cholerae
- 3iwn, 4yb1 – VcGMPR + C-di-GMP + U1 small nuclear ribonucleoprotein
- 3mum, 3mur, 3mut - VcGMPR (mutant) + C-di-GMP + U1 small nuclear ribonucleoprotein
- 3muv - VcGMPR (mutant) + C-di-AMP + U1 small nuclear ribonucleoprotein
- 3q3z - GMPR + C-di-GMP – Clostridium acetobutylicum
- 4qk8, 4qka – GMPR + GTP – Thermoanaerobacter pseudethanolicus
- 4qk9 – GMPR + guanosine derivative – Thermovirga lienii
- 4yaz, 4yb0 – GMPR + C-di-GMP - Geobacter
- 3irw, 3mxh – VcGMPR + C-di-GMP + GTP + U1 small nuclear ribonucleoprotein – Vibrio cholerae
- C-di-AMP riboswitch
- Glycine riboswitch
- M-Box riboswitch
- 3pdr – BsMBR + Mn
- 3pdr – BsMBR + Mn
- T-Box riboswitch
- Tetrahydrofolate riboswitch
- Fluoride riboswitch
- Cobalamine riboswitch
- yybp-ykoy riboswitch
- ykkc riboswitch
- 5u3g – TpR + gusanidine – Dikeya dadantii
- 5u3g – TpR + gusanidine – Dikeya dadantii
- PFI riboswitch
- 4znp – TpR + AICAR – synthetic
- 4znp – TpR + AICAR – synthetic
- NICO riboswitch
- 4rum – TpR + Co – synthetic
- 4rum – TpR + Co – synthetic
- ZMP riboswitch
- ZTP riboswitch
- 5btp – TpR + AICAR – Fusobacterium ulcerans
- 5btp – TpR + AICAR – Fusobacterium ulcerans
- Guanidine riboswitch
References
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Michal Harel, Alexander Berchansky, Karsten Theis, Joel L. Sussman