Giardia lamblia 15.5kD RNA binding protein

Experimental Data Snapshot

  • Resolution: 1.81 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.236 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Comparative analysis of the 15.5kD box C/D snoRNP core protein in the primitive eukaryote Giardia lamblia reveals unique structural and functional features.

Biswas, S.Buhrman, G.Gagnon, K.Mattos, C.Brown, B.A.Maxwell, E.S.

(2011) Biochemistry 50: 2907-2918

  • DOI: https://doi.org/10.1021/bi1020474
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Box C/D ribonucleoproteins (RNP) guide the 2'-O-methylation of targeted nucleotides in archaeal and eukaryotic rRNAs. The archaeal L7Ae and eukaryotic 15.5kD box C/D RNP core protein homologues initiate RNP assembly by recognizing kink-turn (K-turn) motifs. The crystal structure of the 15.5kD core protein from the primitive eukaryote Giardia lamblia is described here to a resolution of 1.8 Å. The Giardia 15.5kD protein exhibits the typical α-β-α sandwich fold exhibited by both archaeal L7Ae and eukaryotic 15.5kD proteins. Characteristic of eukaryotic homologues, the Giardia 15.5kD protein binds the K-turn motif but not the variant K-loop motif. The highly conserved residues of loop 9, critical for RNA binding, also exhibit conformations similar to those of the human 15.5kD protein when bound to the K-turn motif. However, comparative sequence analysis indicated a distinct evolutionary position between Archaea and Eukarya. Indeed, assessment of the Giardia 15.5kD protein in denaturing experiments demonstrated an intermediate stability in protein structure when compared with that of the eukaryotic mouse 15.5kD and archaeal Methanocaldococcus jannaschii L7Ae proteins. Most notable was the ability of the Giardia 15.5kD protein to assemble in vitro a catalytically active chimeric box C/D RNP utilizing the archaeal M. jannaschii Nop56/58 and fibrillarin core proteins. In contrast, a catalytically competent chimeric RNP could not be assembled using the mouse 15.5kD protein. Collectively, these analyses suggest that the G. lamblia 15.5kD protein occupies a unique position in the evolution of this box C/D RNP core protein retaining structural and functional features characteristic of both archaeal L7Ae and higher eukaryotic 15.5kD homologues.

  • Organizational Affiliation

    Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ribosomal protein L7Ae
A, B
122Giardia lamblia ATCC 50803Mutation(s): 0 
Gene Names: GL50803_11287
Find proteins for A8BMJ0 (Giardia intestinalis (strain ATCC 50803 / WB clone C6))
Explore A8BMJ0 
Go to UniProtKB:  A8BMJ0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA8BMJ0
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.81 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.236 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 56.876α = 90
b = 40.611β = 100.93
c = 59.937γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-03-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2011-09-07
    Changes: Database references
  • Version 1.3: 2023-09-06
    Changes: Data collection, Database references, Refinement description