Bacterial tRNA(HIS) Guanylyltransferase (Thg1)-Like Protein in complex with ATP

Experimental Data Snapshot

  • Resolution: 2.36 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.202 

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Structural Studies of a Bacterial tRNA(HIS) Guanylyltransferase (Thg1)-Like Protein, with Nucleotide in the Activation and Nucleotidyl Transfer Sites.

Hyde, S.J.Rao, B.S.Eckenroth, B.E.Jackman, J.E.Doublie, S.

(2013) PLoS One 8: e67465-e67465

  • DOI: https://doi.org/10.1371/journal.pone.0067465
  • Primary Citation of Related Structures:  
    4KGK, 4KGM

  • PubMed Abstract: 

    All nucleotide polymerases and transferases catalyze nucleotide addition in a 5' to 3' direction. In contrast, tRNA(His) guanylyltransferase (Thg1) enzymes catalyze the unusual reverse addition (3' to 5') of nucleotides to polynucleotide substrates. In eukaryotes, Thg1 enzymes use the 3'-5' addition activity to add G-1 to the 5'-end of tRNA(His), a modification required for efficient aminoacylation of the tRNA by the histidyl-tRNA synthetase. Thg1-like proteins (TLPs) are found in Archaea, Bacteria, and mitochondria and are biochemically distinct from their eukaryotic Thg1 counterparts TLPs catalyze 5'-end repair of truncated tRNAs and act on a broad range of tRNA substrates instead of exhibiting strict specificity for tRNA(His). Taken together, these data suggest that TLPs function in distinct biological pathways from the tRNA(His) maturation pathway, perhaps in tRNA quality control. Here we present the first crystal structure of a TLP, from the gram-positive soil bacterium Bacillus thuringiensis (BtTLP). The enzyme is a tetramer like human THG1, with which it shares substantial structural similarity. Catalysis of the 3'-5' reaction with 5'-monophosphorylated tRNA necessitates first an activation step, generating a 5'-adenylylated intermediate prior to a second nucleotidyl transfer step, in which a nucleotide is transferred to the tRNA 5'-end. Consistent with earlier characterization of human THG1, we observed distinct binding sites for the nucleotides involved in these two steps of activation and nucleotidyl transfer. A BtTLP complex with GTP reveals new interactions with the GTP nucleotide in the activation site that were not evident from the previously solved structure. Moreover, the BtTLP-ATP structure allows direct observation of ATP in the activation site for the first time. The BtTLP structural data, combined with kinetic analysis of selected variants, provide new insight into the role of key residues in the activation step.

  • Organizational Affiliation

    Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, United States of America.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Thg1-like uncharacterized protein
A, B, C, D
245Bacillus thuringiensis serovar israelensis ATCC 35646Mutation(s): 0 
Gene Names: RBTH_06728
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on ATP

Download Ideal Coordinates CCD File 
E [auth A],
K [auth B],
O [auth C],
U [auth D]
C10 H16 N5 O13 P3
Query on PO4

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F [auth A],
J [auth A],
P [auth C],
T [auth C]
O4 P
Query on GOL

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I [auth A],
N [auth B],
S [auth C],
X [auth D]
C3 H8 O3
Query on MG

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G [auth A]
H [auth A]
L [auth B]
M [auth B]
Q [auth C]
G [auth A],
H [auth A],
L [auth B],
M [auth B],
Q [auth C],
R [auth C],
V [auth D],
W [auth D]
Experimental Data & Validation

Experimental Data

  • Resolution: 2.36 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.202 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 99.156α = 90
b = 218.343β = 90
c = 126.056γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-08-14
    Type: Initial release
  • Version 1.1: 2024-02-28
    Changes: Data collection, Database references, Derived calculations