6JUS

MsDpo4-DNA complex 6


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.208 

Starting Model: experimental
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Literature

A polar filter in DNA polymerases prevents ribonucleotide incorporation.

Johnson, M.K.Kottur, J.Nair, D.T.

(2019) Nucleic Acids Res 47: 10693-10705

  • DOI: https://doi.org/10.1093/nar/gkz792
  • Primary Citation of Related Structures:  
    6JUL, 6JUM, 6JUN, 6JUO, 6JUP, 6JUQ, 6JUR, 6JUS

  • PubMed Abstract: 

    The presence of ribonucleotides in DNA can lead to genomic instability and cellular lethality. To prevent adventitious rNTP incorporation, the majority of the DNA polymerases (dPols) possess a steric filter. The dPol named MsDpo4 (Mycobacterium smegmatis) naturally lacks this steric filter and hence is capable of rNTP addition. The introduction of the steric filter in MsDpo4 did not result in complete abrogation of the ability of this enzyme to incorporate ribonucleotides. In comparison, DNA polymerase IV (PolIV) from Escherichia coli exhibited stringent selection for deoxyribonucleotides. A comparison of MsDpo4 and PolIV led to the discovery of an additional polar filter responsible for sugar selectivity. Thr43 represents the filter in PolIV and this residue forms interactions with the incoming nucleotide to draw it closer to the enzyme surface. As a result, the 2'-OH in rNTPs will clash with the enzyme surface, and therefore ribonucleotides cannot be accommodated in the active site in a conformation compatible with productive catalysis. The substitution of the equivalent residue in MsDpo4-Cys47, with Thr led to a drastic reduction in the ability of the mycobacterial enzyme to incorporate rNTPs. Overall, our studies evince that the polar filter serves to prevent ribonucleotide incorporation by dPols.


  • Organizational Affiliation

    Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001, India.


Macromolecules

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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase IVA,
D [auth F]
356Mycolicibacterium smegmatis MC2 155Mutation(s): 0 
Gene Names: dinBMSMEG_1014MSMEG_2294
EC: 2.7.7.7
UniProt
Find proteins for A0QR77 (Mycolicibacterium smegmatis (strain ATCC 700084 / mc(2)155))
Explore A0QR77 
Go to UniProtKB:  A0QR77
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0QR77
Sequence Annotations
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  • Reference Sequence

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Entity ID: 2
MoleculeChains LengthOrganismImage
DNA (5'-D(*TP*CP*TP*GP*GP*GP*GP*TP*CP*CP*TP*AP*G)-3')B,
C,
E [auth G],
F [auth H]
18Mycolicibacterium smegmatis
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.206 
  • R-Value Observed: 0.208 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 53.73α = 90
b = 80.34β = 90
c = 208.72γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
Cootmodel building
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Department of Biotechnology (India)IndiaIntramural

Revision History  (Full details and data files)

  • Version 1.0: 2020-02-19
    Type: Initial release
  • Version 1.1: 2023-11-22
    Changes: Data collection, Database references, Derived calculations, Refinement description