1u8d

From Proteopedia

Revision as of 01:22, 25 November 2007

Guanine riboswitch bound to hypoxanthine

Overview

Riboswitches are genetic regulatory elements found in the 5' untranslated, region of messenger RNA that act in the absence of protein cofactors. They, are broadly distributed across bacteria and account for the regulation of, more than 2% of all genes in Bacillus subtilis, underscoring their, importance in the control of cellular metabolism. The 5' untranslated, region of many mRNAs of genes involved in purine metabolism and transport, contain a guanine-responsive riboswitch that directly binds guanine, hypoxanthine or xanthine to terminate transcription. Here we report the, crystal structure at 1.95 A resolution of the purine-binding domain of the, guanine riboswitch from the xpt-pbuX operon of B. subtilis bound to, hypoxanthine, a prevalent metabolite in the bacterial purine salvage, pathway. This structure reveals a complex RNA fold involving several, phylogenetically conserved nucleotides that create a binding pocket that, almost completely envelops the ligand. Hypoxanthine functions to stabilize, this structure and to promote the formation of a downstream, transcriptional terminator element, thereby providing a mechanism for, directly repressing gene expression in response to an increase in, intracellular concentrations of metabolite.

About this Structure

1U8D is a Protein complex structure of sequences from [1] with SPD, ACT, NCO and HPA as ligands. Full crystallographic information is available from OCA.

Reference

Structure of a natural guanine-responsive riboswitch complexed with the metabolite hypoxanthine., Batey RT, Gilbert SD, Montange RK, Nature. 2004 Nov 18;432(7015):411-5. PMID:15549109

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