Summary information and primary citation
- PDB-id
-
3gx5;
DSSR-derived features in text and
JSON formats
- Class
- RNA
- Method
- X-ray (2.402 Å)
- Summary
- Crystal structure of t. tencongensis sam-i riboswitch
variant a94g-u34 bound with sam
- Reference
-
Montange RK, Mondragon E, van Tyne D, Garst AD, Ceres P,
Batey RT (2010): "Discrimination
between Closely Related Cellular Metabolites by the SAM-I
Riboswitch." J.Mol.Biol.,
396, 761-772. doi: 10.1016/j.jmb.2009.12.007.
- Abstract
- The SAM-I riboswitch is a cis-acting element of genetic
control found in bacterial mRNAs that specifically binds
S-adenosylmethionine (SAM). We previously determined the
2.9-A X-ray crystal structure of the effector-binding
domain of this RNA element, revealing details of RNA-ligand
recognition. To improve this structure, variations were
made to the RNA sequence to alter lattice contacts,
resulting in a 0.5-A improvement in crystallographic
resolution and allowing for a more accurate refinement of
the crystallographic model. The basis for SAM specificity
was addressed by a structural analysis of the RNA complexed
to S-adenosylhomocysteine (SAH) and sinefungin and by
measuring the affinity of SAM and SAH for a series of
mutants using isothermal titration calorimetry. These data
illustrate the importance of two universally conserved base
pairs in the RNA that form electrostatic interactions with
the positively charged sulfonium group of SAM, thereby
providing a basis for discrimination between SAM and
SAH.
