Summary information and primary citation
- PDB-id
-
3npq;
DSSR-derived features in text and
JSON formats
- Class
- RNA
- Method
- X-ray (2.18 Å)
- Summary
- Structure of the s-adenosylhomocysteine riboswitch at
2.18 a
- Reference
-
Edwards AL, Reyes FE, Heroux A, Batey RT (2010):
"Structural
basis for recognition of S-adenosylhomocysteine by
riboswitches." Rna, 16,
2144-2155. doi: 10.1261/rna.2341610.
- Abstract
- S-adenosyl-(L)-homocysteine (SAH) riboswitches are
regulatory elements found in bacterial mRNAs that
up-regulate genes involved in the S-adenosyl-(L)-methionine
(SAM) regeneration cycle. To understand the structural
basis of SAH-dependent regulation by RNA, we have solved
the structure of its metabolite-binding domain in complex
with SAH. This structure reveals an unusual pseudoknot
topology that creates a shallow groove on the surface of
the RNA that binds SAH primarily through interactions with
the adenine ring and methionine main chain atoms and
discriminates against SAM through a steric mechanism.
Chemical probing and calorimetric analysis indicate that
the unliganded RNA can access bound-like conformations that
are significantly stabilized by SAH to direct folding of
the downstream regulatory switch. Strikingly, we find that
metabolites bearing an adenine ring, including ATP, bind
this aptamer with sufficiently high affinity such that
normal intracellular concentrations of these compounds may
influence regulation of the riboswitch.
