9CHW

Crystal structure of human polymerase eta with incoming dAMPnPP nucleotide opposite threofuranosyl thymidine in DNA template


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.16 Å
  • R-Value Free: 0.210 
  • R-Value Work: 0.143 
  • R-Value Observed: 0.147 

Starting Model: experimental
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This is version 1.2 of the entry. See complete history


Literature

DNA Replication across alpha-l-(3'-2')-Threofuranosyl Nucleotides Mediated by Human DNA Polymerase eta.

Tomar, R.Ghodke, P.P.Patra, A.Smyth, E.Pontarelli, A.Copp, W.Guengerich, F.P.Chaput, J.C.Wilds, C.J.Stone, M.P.Egli, M.

(2024) Biochemistry 63: 2425-2439

  • DOI: https://doi.org/10.1021/acs.biochem.4c00387
  • Primary Citation of Related Structures:  
    9CHW, 9CI9, 9CIH, 9CIQ, 9CJ9

  • PubMed Abstract: 

    α-l-(3'-2')-Threofuranosyl nucleic acid (TNA) pairs with itself, cross-pairs with DNA and RNA, and shows promise as a tool in synthetic genetics, diagnostics, and oligonucleotide therapeutics. We studied in vitro primer insertion and extension reactions catalyzed by human trans-lesion synthesis (TLS) DNA polymerase η (hPol η) opposite a TNA-modified template strand without and in combination with O 4 -alkyl thymine lesions. Across TNA-T (tT), hPol η inserted mostly dAMP and dGMP, dTMP and dCMP with lower efficiencies, followed by extension of the primer to a full-length product. hPol η inserted dAMP opposite O 4 -methyl and -ethyl analogs of tT, albeit with reduced efficiencies relative to tT. Crystal structures of ternary hPol η complexes with template tT and O 4 -methyl tT at the insertion and extension stages demonstrated that the shorter backbone and different connectivity of TNA compared to DNA (3' → 2' versus 5' → 3', respectively) result in local differences in sugar orientations, adjacent phosphate spacings, and directions of glycosidic bonds. The 3'-OH of the primer's terminal thymine was positioned at 3.4 Å on average from the α-phosphate of the incoming dNTP, consistent with insertion opposite and extension past the TNA residue by hPol η. Conversely, the crystal structure of a ternary hPol η·DNA·tTTP complex revealed that the primer's terminal 3'-OH was too distant from the tTTP α-phosphate, consistent with the inability of the polymerase to incorporate TNA. Overall, our study provides a better understanding of the tolerance of a TLS DNA polymerase vis-à-vis unnatural nucleotides in the template and as the incoming nucleoside triphosphate.


  • Organizational Affiliation

    Department of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States.


Macromolecules

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase eta435Homo sapiensMutation(s): 0 
Gene Names: POLHRAD30RAD30AXPV
EC: 2.7.7.7
UniProt & NIH Common Fund Data Resources
Find proteins for Q9Y253 (Homo sapiens)
Explore Q9Y253 
Go to UniProtKB:  Q9Y253
PHAROS:  Q9Y253
GTEx:  ENSG00000170734 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9Y253
Sequence Annotations
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  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
DNA (5'-D(*CP*AP*TP*(TFT)P*AP*TP*GP*AP*CP*GP*CP*T)-3')B [auth T]12synthetic construct
Sequence Annotations
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  • Reference Sequence

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Entity ID: 3
MoleculeChains LengthOrganismImage
DNA (5'-D(*AP*GP*CP*GP*TP*CP*AP*T)-3')C [auth P]8synthetic construct
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

Unit Cell:
Length ( Å )Angle ( ˚ )
a = 98.686α = 90
b = 98.686β = 90
c = 82.062γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing
Cootmodel building

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Cancer Institute (NIH/NCI)United StatesR01ES029357
National Institutes of Health/National Cancer Institute (NIH/NCI)United States2P01CA160032-26A1

Revision History  (Full details and data files)

  • Version 1.0: 2024-09-18
    Type: Initial release
  • Version 1.1: 2024-09-25
    Changes: Database references
  • Version 1.2: 2024-10-16
    Changes: Database references, Structure summary