6LAX | pdb_00006lax

the mutant SAM-VI riboswitch (U6C) bound to SAM


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 
    0.239 (Depositor), 0.241 (DCC) 
  • R-Value Work: 
    0.189 (Depositor), 0.194 (DCC) 
  • R-Value Observed: 
    0.191 (Depositor) 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.3 of the entry. See complete history

Literature

SAM-VI riboswitch structure and signature for ligand discrimination.

Sun, A.Gasser, C.Li, F.Chen, H.Mair, S.Krasheninina, O.Micura, R.Ren, A.

(2019) Nat Commun 10: 5728-5728

  • DOI: https://doi.org/10.1038/s41467-019-13600-9
  • Primary Citation Related Structures: 
    6LAS, 6LAU, 6LAX, 6LAZ

  • PubMed Abstract: 

    Riboswitches are metabolite-sensing, conserved domains located in non-coding regions of mRNA that are central to regulation of gene expression. Here we report the first three-dimensional structure of the recently discovered S-adenosyl-L-methionine responsive SAM-VI riboswitch. SAM-VI adopts a unique fold and ligand pocket that are distinct from all other known SAM riboswitch classes. The ligand binds to the junctional region with its adenine tightly intercalated and Hoogsteen base-paired. Furthermore, we reveal the ligand discrimination mode of SAM-VI by additional X-ray structures of this riboswitch bound to S-adenosyl-L-homocysteine and a synthetic ligand mimic, in combination with isothermal titration calorimetry and fluorescence spectroscopy to explore binding thermodynamics and kinetics. The structure is further evaluated by analysis of ligand binding to SAM-VI mutants. It thus provides a thorough basis for developing synthetic SAM cofactors for applications in chemical and synthetic RNA biology.


  • Organizational Affiliation
    • Life Sciences Institute, Zhejiang University, 310058, Hangzhou, Zhejiang, China.

Macromolecule Content 

  • Total Structure Weight: 69.22 kDa 
  • Atom Count: 4,661 
  • Modeled Residue Count: 385 
  • Deposited Residue Count: 389 
  • Unique protein chains: 1
  • Unique nucleic acid chains: 1

Macromolecules


Find similar proteins by:|  3D Structure
Entity ID: 2
MoleculeChains  Sequence LengthOrganismDetailsImage
U1 small nuclear ribonucleoprotein AB [auth D],
C,
D [auth E]
93Homo sapiensMutation(s): 3 
Gene Names: SNRPA
UniProt & NIH Common Fund Data Resources
Find proteins for P09012 (Homo sapiens)
Explore P09012 
Go to UniProtKB:  P09012
PHAROS:  P09012
GTEx:  ENSG00000077312 
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP09012
Sequence Annotations
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Reference Sequence
Find similar nucleic acids by:  (by identity cutoff) 
Entity ID: 1
MoleculeChains LengthOrganismImage
RNA (55-MER)A,
E [auth B]
55Bifidobacterium angulatum
Sequence Annotations
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Reference Sequence

Small Molecules

Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
MSE
Query on MSE
B [auth D],
C,
D [auth E]
L-PEPTIDE LINKINGC5 H11 N O2 SeMET

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free:  0.239 (Depositor), 0.241 (DCC) 
  • R-Value Work:  0.189 (Depositor), 0.194 (DCC) 
  • R-Value Observed: 0.191 (Depositor) 
Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 45.892α = 90
b = 86.942β = 99.19
c = 93.626γ = 90
Software Package:
Software NamePurpose
HKL-2000data scaling
PHENIXrefinement
PDB_EXTRACTdata extraction
HKL-2000data reduction
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Natural Science Foundation of ChinaChina31870810, 91640104 and 31670826

Revision History  (Full details and data files)

  • Version 1.0: 2020-01-01
    Type: Initial release
  • Version 1.1: 2023-11-22
    Changes: Data collection, Database references, Refinement description
  • Version 1.2: 2024-10-23
    Changes: Structure summary
  • Version 1.3: 2025-03-12
    Changes: Database references