8VDT

DNA Ligase 1 with nick DNA 3'rA:T


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.78 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.207 

Starting Model: experimental
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Literature

Structures of LIG1 provide a mechanistic basis for understanding a lack of sugar discrimination against a ribonucleotide at the 3'-end of nick DNA.

Balu, K.E.Gulkis, M.Almohdar, D.Caglayan, M.

(2024) J Biol Chem 300: 107216-107216

  • DOI: https://doi.org/10.1016/j.jbc.2024.107216
  • Primary Citation of Related Structures:  
    8VDN, 8VDS, 8VDT, 8VZL, 8VZM

  • PubMed Abstract: 

    Human DNA ligase 1 (LIG1) is the main replicative ligase that seals Okazaki fragments during nuclear replication and finalizes DNA repair pathways by joining DNA ends of the broken strand breaks in the three steps of the ligation reaction. LIG1 can tolerate the RNA strand upstream of the nick, yet an atomic insight into the sugar discrimination mechanism by LIG1 against a ribonucleotide at the 3'-terminus of nick DNA is unknown. Here, we determined X-ray structures of LIG1/3'-RNA-DNA hybrids and captured the ligase during pre- and post-step 3 the ligation reaction. Furthermore, the overlays of 3'-rA:T and 3'-rG:C step 3 structures with step 2 structures of canonical 3'-dA:T and 3'-dG:C uncover a network of LIG1/DNA interactions through Asp570 and Arg871 side chains with 2'-OH of the ribose at nick showing a final phosphodiester bond formation and the other ligase active site residues surrounding the AMP site. Finally, we demonstrated that LIG1 can ligate the nick DNA substrates with pre-inserted 3'-ribonucleotides as efficiently as Watson-Crick base-paired ends in vitro. Together, our findings uncover a novel atomic insight into a lack of sugar discrimination by LIG1 and the impact of improper sugar on the nick sealing of ribonucleotides at the last step of DNA replication and repair.


  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA.


Macromolecules

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA ligase 1658Homo sapiensMutation(s): 0 
Gene Names: LIG1
EC: 6.5.1.1
UniProt & NIH Common Fund Data Resources
Find proteins for P18858 (Homo sapiens)
Explore P18858 
Go to UniProtKB:  P18858
PHAROS:  P18858
GTEx:  ENSG00000105486 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP18858
Sequence Annotations
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  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
DNA/RNA (5'-D(*GP*CP*TP*GP*AP*TP*GP*CP*GP*T)-R(P*A)-D(P*GP*TP*CP*GP*GP*AP*C)-3')18synthetic construct
Sequence Annotations
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  • Reference Sequence

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Entity ID: 3
MoleculeChains LengthOrganismImage
DNA (5'-D(*GP*TP*CP*CP*GP*AP*CP*TP*AP*CP*GP*CP*AP*TP*CP*AP*GP*C)-3')18synthetic construct
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download Ideal Coordinates CCD File 
D [auth B]PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.78 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.207 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.17α = 90
b = 115.342β = 90
c = 125.002γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

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 States1R35GM147111

Revision History  (Full details and data files)

  • Version 1.0: 2024-05-22
    Type: Initial release