9YXV | pdb_00009yxv

Cryo-EM structure of the core region of cIL-U1A-Fab1R-PGA1-sfFab quaternary complex at 2.9 A resolution


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 2.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Starting Models: experimental
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wwPDB Validation 3D Report Full Report

Validation slider image for 9YXV

This is version 2.0 of the entry. See complete history

Literature

A universal Fab targeting a conserved U1A-RNA epitope for RNA structure determination by cryo-EM.

Filippova, E.V.Krochmal, D.Mukherjee, S.Piccirilli, J.A.Kossiakoff, A.A.

(2026) Nucleic Acids Res 54

  • DOI: https://doi.org/10.1093/nar/gkag502
  • Primary Citation Related Structures: 
    9YXV, 9Z6I

  • PubMed Abstract: 

    Recent advances in cryo-electron microscopy (cryo-EM) have made antigen-binding fragments (Fabs) essential tools in the field of structural biology. Fabs facilitate image alignment, thereby enhancing three-dimensional (3D) reconstruction, and increase the effective size of proteins, aiding in their structural elucidation. In this study, we sought to broaden the use of Fabs as fiducial markers to elucidate the structures of RNA molecules. Identifying an appropriate Fab for a specific RNA target can be particularly challenging due to RNA's inherent flexibility and tendency to assume multiple conformations, which complicate the process and prolong the structure determination timeline. To address this challenge, we designed a universal Fab that specifically recognizes a U1A-RNA epitope, thereby reducing the need for Fab selection tailored to each individual RNA target. We determined the cryo-EM structure of the class I ligase ribozyme complexed with a portable U1hpII loop bound to the U1A protein and the Fab. The resulting structure revealed that the Fab interacts with a conserved U1A-RNA binding region, which can be engineered into other RNA molecules. This strategy presents significant potential for streamlining the structural determination of various RNAs, which are essential for biological and biomedical research.


  • Organizational Affiliation
    • Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, United States.

Macromolecule Content 

  • Total Structure Weight: 130.6 kDa 
  • Atom Count: 6,554 
  • Modeled Residue Count: 825 
  • Deposited Residue Count: 1,162 
  • Unique protein chains: 6
  • Unique nucleic acid chains: 1

Macromolecules


Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
U1 small nuclear ribonucleoprotein A97Homo sapiensMutation(s): 0 
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 proteins by:|  3D Structure
Entity ID: 3
MoleculeChains  Sequence LengthOrganismDetailsImage
Protein G67Streptococcus sp. 'group GMutation(s): 0 
UniProt
Find proteins for P19909 (Streptococcus sp. group G)
Explore P19909 
Go to UniProtKB:  P19909
Entity Groups
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP19909
Sequence Annotations
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Reference Sequence
Find similar proteins by:|  3D Structure
Entity ID: 4
MoleculeChains  Sequence LengthOrganismDetailsImage
sfFab18 light chain239Homo sapiensMutation(s): 0 
Find similar proteins by:|  3D Structure
Entity ID: 5
MoleculeChains  Sequence LengthOrganismDetailsImage
sfFab18 heavy chain258Homo sapiensMutation(s): 0 
Find similar proteins by:|  3D Structure
Entity ID: 6
MoleculeChains  Sequence LengthOrganismDetailsImage
Fab1R heavy chainF [auth H]264Homo sapiensMutation(s): 0 
Find similar proteins by:|  3D Structure
Entity ID: 7
MoleculeChains  Sequence LengthOrganismDetailsImage
Fab1R light chainG [auth L]219Homo sapiensMutation(s): 0 
Find similar nucleic acids by:  Sequence
Entity ID: 2
MoleculeChains LengthOrganismImage
Hairpin II of the U1 snRNA (U1hpII)18synthetic construct
Sequence Annotations
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Reference Sequence

Small Molecules

Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
DMU
(Subject of Investigation/LOI)

Query on DMU



Download:Ideal Coordinates CCD File
H [auth A]DECYL-BETA-D-MALTOPYRANOSIDE
C22 H42 O11
WOQQAWHSKSSAGF-WXFJLFHKSA-N

Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 2.90 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion
MODEL REFINEMENTPHENIX
MODEL REFINEMENTCoot
RECONSTRUCTIONcryoSPARC3.3.1

Structure Validation

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Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United States--

Revision History  (Full details and data files)

  • Version 1.0: 2026-05-27
    Type: Initial release
  • Version 2.0: 2026-06-03
    Changes: Advisory, Data collection, Database references, Non-polymer description, Polymer sequence, Source and taxonomy, Structure summary