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| | ==Crystal structure of apo alpha-1 giardin== | | ==Crystal structure of apo alpha-1 giardin== |
| - | <StructureSection load='4evf' size='340' side='right' caption='[[4evf]], [[Resolution|resolution]] 1.90Å' scene=''> | + | <StructureSection load='4evf' size='340' side='right'caption='[[4evf]], [[Resolution|resolution]] 1.90Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[4evf]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Giardia_intestinalis Giardia intestinalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4EVF OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4EVF FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[4evf]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Giardia_intestinalis Giardia intestinalis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4EVF OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4EVF FirstGlance]. <br> |
| - | </td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4evh|4evh]]</td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.9Å</td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4evf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4evf OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4evf RCSB], [http://www.ebi.ac.uk/pdbsum/4evf PDBsum]</span></td></tr> | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4evf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4evf OCA], [https://pdbe.org/4evf PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4evf RCSB], [https://www.ebi.ac.uk/pdbsum/4evf PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4evf ProSAT]</span></td></tr> |
| | </table> | | </table> |
| - | <div style="background-color:#fffaf0;">
| + | == Function == |
| - | == Publication Abstract from PubMed == | + | [https://www.uniprot.org/uniprot/GIA1_GIAIN GIA1_GIAIN] Giardins are involved in parasite attachment to the intestinal mucosa and in the cytoskeletal disassembly and reassembly that marks the transition from infectious trophozoite to transmissible cyst. They may interact with other cytoskeletal proteins such as microtubules in the microribbons or crossbridges, to maintain the integrity of the ventral disk. |
| - | Alpha-giardins constitute the annexin proteome (group E annexins) in the intestinal protozoan parasite Giardia and, as such, represent the evolutionary oldest eukaryotic annexins. The dominance of alpha-giardins in the cytoskeleton of Giardia with its greatly reduced actin content emphasises the importance of the alpha-giardins for the structural integrity of the parasite, which is particularly critical in the transformation stage between cyst and trophozoite. In this study, we report the crystal structures of the apo- and calcium-bound forms of alpha1-giardin, a protein localised to the plasma membrane of Giardia trophozoites that has recently been identified as a vaccine target. The calcium-bound crystal structure of alpha1-giardin revealed the presence of a type III site in the first repeat as known from other annexin structures, as well as a novel calcium binding site situated between repeats I and IV. By means of comparison, the crystal structures of three different alpha-giardins known to date indicate that these proteins engage different calcium coordination schemes, among each other, as well as compared to annexins of groups A-D. Evaluation of the calcium-dependent binding to acidic phosphoplipid membranes revealed that this process is not only mediated but also regulated by the environmental calcium concentration. Uniquely within the large family of annexins, alpha1-giardin disengages from the phospholipid membrane at high calcium concentrations possibly due to formation of a dimeric species. The observed behaviour is in line with changing calcium levels experienced by the parasite during excystation and may thus provide first insights into the molecular mechanisms underpinning the transformation and survival of the parasite in the host.
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| - | Alpha-1 giardin is an annexin with highly unusual calcium-regulated mechanisms.,Weeratunga SK, Osman A, Hu NJ, Wang CK, Mason L, Svard S, Hope G, Jones MK, Hofmann A J Mol Biol. 2012 Oct 19;423(2):169-81. doi: 10.1016/j.jmb.2012.06.041. Epub 2012 , Jul 10. PMID:22796298<ref>PMID:22796298</ref>
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| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| - | </div>
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| - | == References ==
| + | |
| - | <references/>
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| | [[Category: Giardia intestinalis]] | | [[Category: Giardia intestinalis]] |
| - | [[Category: Hofmann, A]] | + | [[Category: Large Structures]] |
| - | [[Category: Weeratunga, S]] | + | [[Category: Hofmann A]] |
| - | [[Category: Annexin]] | + | [[Category: Weeratunga S]] |
| - | [[Category: Calcium-binding protein]]
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| - | [[Category: Membrane-binding protein]]
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| - | [[Category: Metal binding protein]]
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