3SUX

Crystal structure of THF riboswitch, bound with THF


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.190 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Long-range pseudoknot interactions dictate the regulatory response in the tetrahydrofolate riboswitch.

Huang, L.Ishibe-Murakami, S.Patel, D.J.Serganov, A.

(2011) Proc Natl Acad Sci U S A 108: 14801-14806

  • DOI: 10.1073/pnas.1111701108
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Tetrahydrofolate (THF), a biologically active form of the vitamin folate (B(9)), is an essential cofactor in one-carbon transfer reactions. In bacteria, expression of folate-related genes is controlled by feedback modulation in response to specific b ...

    Tetrahydrofolate (THF), a biologically active form of the vitamin folate (B(9)), is an essential cofactor in one-carbon transfer reactions. In bacteria, expression of folate-related genes is controlled by feedback modulation in response to specific binding of THF and related compounds to a riboswitch. Here, we present the X-ray structures of the THF-sensing domain from the Eubacterium siraeum riboswitch in the ligand-bound and unbound states. The structure reveals an "inverted" three-way junctional architecture, most unusual for riboswitches, with the junction located far from the regulatory helix P1 and not directly participating in helix P1 formation. Instead, the three-way junction, stabilized by binding to the ligand, aligns the riboswitch stems for long-range tertiary pseudoknot interactions that contribute to the organization of helix P1 and therefore stipulate the regulatory response of the riboswitch. The pterin moiety of the ligand docks in a semiopen pocket adjacent to the junction, where it forms specific hydrogen bonds with two moderately conserved pyrimidines. The aminobenzoate moiety stacks on a guanine base, whereas the glutamate moiety does not appear to make strong interactions with the RNA. In contrast to other riboswitches, these findings demonstrate that the THF riboswitch uses a limited number of available determinants for ligand recognition. Given that modern antibiotics target folate metabolism, the THF riboswitch structure provides insights on mechanistic aspects of riboswitch function and may help in manipulating THF levels in pathogenic bacteria.


    Organizational Affiliation

    Structural Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA. huanglilisioc@hotmail.com



Macromolecules

Find similar nucleic acids by: Sequence   |  Structure

Entity ID: 1
MoleculeChainsLengthOrganism
RiboswitchX101[Eubacterium] siraeum V10Sc8a
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
THF
Query on THF

Download CCD File 
X
5-HYDROXYMETHYLENE-6-HYDROFOLIC ACID
C20 H23 N7 O7
IIEPLRAFVCMHQF-STQMWFEESA-N
 Ligand Interaction
NA
Query on NA

Download CCD File 
X
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.90 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.190 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 126.173α = 90
b = 126.173β = 90
c = 149.222γ = 120
Software Package:
Software NamePurpose
CBASSdata collection
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling
REFMACphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-09-14
    Type: Initial release
  • Version 1.1: 2012-03-14
    Changes: Database references