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| | {{STRUCTURE_2iic| PDB=2iic | SCENE= }} | | {{STRUCTURE_2iic| PDB=2iic | SCENE= }} |
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| - | '''Calcium bound structure of alpha-11 giardin'''
| + | ===Calcium bound structure of alpha-11 giardin=== |
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| - | ==Overview==
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| - | 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.
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Calcium-protein complex]] | | [[Category: Calcium-protein complex]] |
| | [[Category: Helix-turn-helix]] | | [[Category: Helix-turn-helix]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:32:29 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 04:16:04 2008'' |
Revision as of 01:16, 29 July 2008
Template:STRUCTURE 2iic
Calcium bound structure of alpha-11 giardin
Template:ABSTRACT PUBMED 17355882
About this Structure
2IIC is a Single protein structure of sequence from Giardia intestinalis. Full crystallographic information is available from OCA.
Reference
Apo and calcium-bound crystal structures of Alpha-11 giardin, an unusual annexin from Giardia lamblia., Pathuri P, Nguyen ET, Svard SG, Luecke H, J Mol Biol. 2007 Apr 27;368(2):493-508. Epub 2007 Feb 20. PMID:17355882
Page seeded by OCA on Tue Jul 29 04:16:04 2008
