Sandbox Reserved 1576

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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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Contents

Adenine Riboswitch

Overview

Riboswitches are metabolite-sensing-mRNAs that interact with small ligands and direct expression of the genes involved in their metabolism. Riboswitches contain sensing "aptamer" modules, which create ligand-induced structural changes, that allow for controlling gene expression. They form tuning-fork structures, where the prongs go through hairpin loop interactions, and the internal bubble zips up to form an adenine binding pocket. The bound purines are held by hydrogen bonds. The encapsulated adenine is paired to cytosine through Watson-Crick base pairing.[1]

A-riboswitch-adenenine complex 3D model

Drag the structure with the mouse to rotate

Function

Riboswitches are used as a form of genetic control in some bacteria, where they modulate the expression of transport and metabolic proteins. The adenine and guanine riboswitches form nearly identical binding pockets since they are both purines. The single nucleotide in the core forms a Watson-Crick base pair with its ligand. The structure of the adenine riboswitch bound to its ligand creates RNA's ability to use A-minor motifs and base tetrads, which causes the folding required to create the binding pockets. This provides the infrastructure for targeting and discrimination between similar metabolites. The adenine riboswitch is found in B. subtilis, C. perfringens, and V. vulnificus. These bacteria contain the ydhL gene, which allows the bacteria to sense adenine. It can also differentiate against guanine and purines.[1]



References

  1. ↑ 1.0 1.1 1.2 1.3 Serganov A, Yuan YR, Pikovskaya O, Polonskaia A, Malinina L, Phan AT, Hobartner C, Micura R, Breaker RR, Patel DJ. Structural basis for discriminative regulation of gene expression by adenine- and guanine-sensing mRNAs. Chem Biol. 2004 Dec;11(12):1729-41. PMID:15610857 doi:S1074-5521(04)00343-6
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