PDBsum entry 2iic

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protein metals Protein-protein interface(s) links
Metal binding protein PDB id
Protein chains
302 a.a. *
_CA ×4
Waters ×111
* Residue conservation analysis
PDB id:
Name: Metal binding protein
Title: Calcium bound structure of alpha-11 giardin
Structure: Alpha-11 giardin. Chain: a, b, c, d. Engineered: yes
Source: Giardia intestinalis. Organism_taxid: 5741. Expressed in: escherichia coli. Expression_system_taxid: 562.
2.93Å     R-factor:   0.264     R-free:   0.306
Authors: P.Pathuri,E.T.Nguyen,H.Luecke
Key ref:
P.Pathuri et al. (2007). Apo and Calcium-bound Crystal Structures of Alpha-11 Giardin, an Unusual Annexin from Giardia lamblia. J Mol Biol, 368, 493-508. PubMed id: 17355882 DOI: 10.1016/j.jmb.2007.02.016
27-Sep-06     Release date:   17-Apr-07    
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Protein chains
Pfam   ArchSchema ?
Q4VPP2  (Q4VPP2_GIAIN) -  Alpha-11 giardin
307 a.a.
302 a.a.
Key:    PfamB domain  Secondary structure  CATH domain

 Gene Ontology (GO) functional annotation 
  GO annot!
  Biological process     cytoskeleton organization   1 term 
  Biochemical function     calcium-dependent phospholipid binding     3 terms  


DOI no: 10.1016/j.jmb.2007.02.016 J Mol Biol 368:493-508 (2007)
PubMed id: 17355882  
Apo and Calcium-bound Crystal Structures of Alpha-11 Giardin, an Unusual Annexin from Giardia lamblia.
P.Pathuri, E.T.Nguyen, S.G.Svärd, H.Luecke.
Alpha-11 giardin is a member of the multi-gene alpha-giardin family in the intestinal protozoan, Giardia lamblia. This gene family shares an ancestry with the annexin super family, whose common characteristic is calcium-dependent binding to membranes that contain acidic phospholipids. Several alpha giardins are highly expressed during parasite-induced diarrhea in humans. Despite being a member of a large family of proteins, little is known about the function and cellular localization of alpha-11 giardin, although giardins are often associated with the cytoskeleton. It has been shown that Giardia exhibits high levels of alpha-11 giardin mRNA transcript throughout its life cycle; however, constitutive over-expression of this protein is lethal to the parasite. Determining the three-dimensional structure of an alpha-giardin is essential to identifying functional domains shared in the alpha-giardin family. Here we report the crystal structures of the apo and Ca(2+)-bound forms of alpha-11 giardin, the first alpha giardin to be characterized structurally. Crystals of apo and Ca(2+)-bound alpha-11 giardin diffracted to 1.1 A and 2.93 A, respectively. The crystal structure of selenium-substituted apo alpha-11 giardin reveals a planar array of four tandem repeats of predominantly alpha-helical domains, reminiscent of previously determined annexin structures, making this the highest-resolution structure of an annexin to date. The apo alpha-11 giardin structure also reveals a hydrophobic core formed between repeats I/IV and II/III, a region typically hydrophilic in other annexins. Surprisingly, the Ca(2+)-bound structure contains only a single calcium ion, located in the DE loop of repeat I and coordinated differently from the two types of calcium sites observed in previous annexin structures. The apo and Ca(2+)-bound alpha-11 giardin structures assume overall similar conformations; however, Ca(2+)-bound alpha-11 giardin crystallized in a lower-symmetry space group with four molecules in the asymmetric unit. Vesicle-binding studies suggest that alpha-11 giardin, unlike most other annexins, does not bind to vesicles composed of acidic phospholipids in a calcium-dependent manner.
  Selected figure(s)  
Figure 7.
Figure 7. Overlay of alpha-11 giardin (blue) and annexin A4 (orange) crystal structures. (a) Side view of the structure and (b) top view from the convex side. The N termini (Nt) of alpha-11 giardin and annexin A4 are labeled in their respective colors. Superposition of the alpha-11 giardin and annexin A4 structures was performed in Coot^39 and the Figures were produced with the molecular graphics program Pymol [].
Figure 8.
Figure 8. Arrangement of the four monomers in the asymmetric unit of Ca^2+-bound alpha-11 giardin. Monomer A is shown in yellow, monomer B in purple, monomer C in green and monomer D in teal. Calcium ions bound to the DE loop of repeat I in each of the four monomers are illustrated as red spheres. The Figure was prepared with the molecular graphics program Pymol [].
  The above figures are reprinted by permission from Elsevier: J Mol Biol (2007, 368, 493-508) copyright 2007.  
  Figures were selected by an automated process.  

Literature references that cite this PDB file's key reference

  PubMed id Reference
21105292 A.Hofmann, A.Osman, C.Y.Leow, P.Driguez, D.P.McManus, and M.K.Jones (2010).
Parasite annexins--new molecules with potential for drug and vaccine development.
  Bioessays, 32, 967-976.  
19684283 M.Saric, A.Vahrmann, D.Niebur, V.Kluempers, A.B.Hehl, and H.Scholze (2009).
Dual acylation accounts for the localization of {alpha}19-giardin in the ventral flagellum pair of Giardia lamblia.
  Eukaryot Cell, 8, 1567-1574.  
18441010 N.J.Hu, A.M.Yusof, A.Winter, A.Osman, A.K.Reeve, and A.Hofmann (2008).
The crystal structure of calcium-bound annexin Gh1 from Gossypium hirsutum and its implications for membrane binding mechanisms of plant annexins.
  J Biol Chem, 283, 18314-18322.
PDB code: 3brx
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