3CHK

Calcium bound structure of alpha-14 giardin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.202 

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This is version 1.1 of the entry. See complete history

Literature

Apo and calcium-bound crystal structures of cytoskeletal protein alpha-14 giardin (annexin E1) from the intestinal protozoan parasite Giardia lamblia

Pathuri, P.Nguyen, E.T.Ozorowski, G.Svard, S.G.Luecke, H.

(2009) J.Mol.Biol. 385: 1098-1112

  • DOI: 10.1016/j.jmb.2008.11.012
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Alpha-14 giardin (annexin E1), a member of the alpha giardin family of annexins, has been shown to localize to the flagella of the intestinal protozoan parasite Giardia lamblia. Alpha giardins show a common ancestry with the annexins, a family of pro ...

    Alpha-14 giardin (annexin E1), a member of the alpha giardin family of annexins, has been shown to localize to the flagella of the intestinal protozoan parasite Giardia lamblia. Alpha giardins show a common ancestry with the annexins, a family of proteins most of which bind to phospholipids and cellular membranes in a Ca(2+)-dependent manner and are implicated in numerous membrane-related processes including cytoskeletal rearrangements and membrane organization. It has been proposed that alpha-14 giardin may play a significant role during the cytoskeletal rearrangement during differentiation of Giardia. To gain a better understanding of alpha-14 giardin's mode of action and its biological role, we have determined the three-dimensional structure of alpha-14 giardin and its phospholipid-binding properties. Here, we report the apo crystal structure of alpha-14 giardin determined in two different crystal forms as well as the Ca(2+)-bound crystal structure of alpha-14 giardin, refined to 1.9, 1.6 and 1.65 A, respectively. Although the overall fold of alpha-14 giardin is similar to that of alpha-11 giardin, multiwavelength anomalous dispersion phasing was required to solve the alpha-14 giardin structure, indicating significant structural differences between these two members of the alpha giardin family. Unlike most annexin structures, which typically possess N-terminal domains, alpha-14 giardin is composed of only a core domain, followed by a C-terminal extension that may serve as a ligand for binding to cytoskeletal protein partners in Giardia. In the Ca(2+)-bound structure we detected five bound calcium ions, one of which is a novel, highly coordinated calcium-binding site not previously observed in annexin structures. This novel high-affinity calcium-binding site is composed of seven protein donor groups, a feature rarely observed in crystal structures. In addition, phospholipid-binding assays suggest that alpha-14 giardin exhibits calcium-dependent binding to phospholipids that coordinate cytoskeletal disassembly/assembly during differentiation of the parasite.


    Organizational Affiliation

    Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Alpha-14 giardin
A
337Giardia intestinalisMutation(s): 0 
Gene Names: ANXE1 (ANX21)
Find proteins for Q9NFS4 (Giardia intestinalis)
Go to UniProtKB:  Q9NFS4
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.65 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.202 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 49.301α = 90.00
b = 50.018β = 110.04
c = 71.819γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data collection
PDB_EXTRACTdata extraction
PHASERphasing
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-01-06
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance