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{{Sandbox_Reserved_JMeans}}<!-- PLEASE ADD YOUR CONTENT BELOW HERE --> | {{Sandbox_Reserved_JMeans}}<!-- PLEASE ADD YOUR CONTENT BELOW HERE --> | ||
==SAM | ==SAM Riboswitch== | ||
<StructureSection load=2gis' size='340' side='right' caption='SAM | <StructureSection load='2gis' size='340' side='right' caption='SAM Riboswitch' scene=''> | ||
==Overview== | |||
S-adenosylmethionine (SAM) is a riboswitch, which are structured noncoding RNA domains that selectively bind metabolites and control gene expression. Nearly all examples of the known riboswitches reside in noncoding regions of messenger RNAs where they control transcription or translation.<ref name="ref1">PMID:16810258</ref> | |||
== Structural Highlights == | |||
The key architecture of SAM riboswitch is composed of ligand-induced interactions between one helix and the 3' side of another helix surrounding the SAM ligand, as well as hydrogen bonding interactions between the adenosine base of SAM and interactions between the main chain atoms of methionine with nucleotide interactions. <ref name="ref1" /> | |||
== | The SAM ligand is bound within a pocket created by the <scene name='82/824623/Helix_interaction/2'>Helix Interaction</scene> (purple). The SAM ligand adopts a compact conformation in which the methionine stacks upon the adenine ring, stabilized in part by the π-cation interaction with the amino group pointing toward the adenine ring. Also the compact configuration of SAM creates a hydrogen bonding interaction to helix P3 and van der Waals forces interacting with the minor groove of the P1 helix. <ref name="ref1" /> | ||
The adenine ring of SAM is the central position between five nucleotides. The nucleotides interact by hydrogen bond attractions between themselves and the SAM ligand to stabilize position <scene name='82/824623/Nitrogenous_base_interactions/3'>Nucleotide Interaction</scene>(orange). <ref name="ref1" /> | |||
== | == Function == | ||
Most responses to stimuli are mediated by transcription factors that in some way either turn on or off the production of their regulatory target. Genetic regulation by RNA is often used in bacterial cells. In the use of the SAM riboswitch, the aptamer of tertiary RNA will bind to the SAM ligand where the helices and nucleotides discussed previously hold the ligand in place for productive binding, and also folds around the tertiary RNA once binding takes place. Stable binding of SAM when adequate amounts are present results in it acting as a transcriptional terminator which turns off gene expression. <ref name="ref1" /> | |||
== References == | == References == | ||
(1) Montange, R. K.; Batey, R. T. Structure of the S-Adenosylmethionine Riboswitch Regulatory MRNA Element. Nature 2006, 441 (7097), 1172–1175. https://doi.org/10.1038/nature04819. | |||
Latest revision as of 13:43, 4 December 2019
| This Sandbox is Reserved from September 14, 2021, through May 31, 2022, for use in the class Introduction to Biochemistry taught by User:John Means at the University of Rio Grande, Rio Grande, OH, USA. This reservation includes 5 reserved sandboxes (Sandbox Reserved 1590 through Sandbox Reserved 1594). |
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More help: Help:Editing. For an example of a student Proteopedia page, please see Photosystem II, Tetanospasmin, or Guanine riboswitch. |
SAM Riboswitch
<StructureSection load='2gis' size='340' side='right' caption='SAM Riboswitch' scene=>
Overview
S-adenosylmethionine (SAM) is a riboswitch, which are structured noncoding RNA domains that selectively bind metabolites and control gene expression. Nearly all examples of the known riboswitches reside in noncoding regions of messenger RNAs where they control transcription or translation.[1]
Structural Highlights
The key architecture of SAM riboswitch is composed of ligand-induced interactions between one helix and the 3' side of another helix surrounding the SAM ligand, as well as hydrogen bonding interactions between the adenosine base of SAM and interactions between the main chain atoms of methionine with nucleotide interactions. [1]
The SAM ligand is bound within a pocket created by the Helix Interaction (purple). The SAM ligand adopts a compact conformation in which the methionine stacks upon the adenine ring, stabilized in part by the π-cation interaction with the amino group pointing toward the adenine ring. Also the compact configuration of SAM creates a hydrogen bonding interaction to helix P3 and van der Waals forces interacting with the minor groove of the P1 helix. [1]
The adenine ring of SAM is the central position between five nucleotides. The nucleotides interact by hydrogen bond attractions between themselves and the SAM ligand to stabilize position Nucleotide Interaction(orange). [1]
Function
Most responses to stimuli are mediated by transcription factors that in some way either turn on or off the production of their regulatory target. Genetic regulation by RNA is often used in bacterial cells. In the use of the SAM riboswitch, the aptamer of tertiary RNA will bind to the SAM ligand where the helices and nucleotides discussed previously hold the ligand in place for productive binding, and also folds around the tertiary RNA once binding takes place. Stable binding of SAM when adequate amounts are present results in it acting as a transcriptional terminator which turns off gene expression. [1]
References
(1) Montange, R. K.; Batey, R. T. Structure of the S-Adenosylmethionine Riboswitch Regulatory MRNA Element. Nature 2006, 441 (7097), 1172–1175. https://doi.org/10.1038/nature04819.
