View source for 2q97


==Complex of mammalian actin with toxofilin from toxoplasma gondii==
<StructureSection load='2q97' size='340' side='right'caption='[[2q97]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2q97]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus] and [https://en.wikipedia.org/wiki/Toxoplasma_gondii Toxoplasma gondii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2Q97 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2Q97 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ATP:ADENOSINE-5-TRIPHOSPHATE'>ATP</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=HIC:4-METHYL-HISTIDINE'>HIC</scene></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=2q97 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2q97 OCA], [https://pdbe.org/2q97 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2q97 RCSB], [https://www.ebi.ac.uk/pdbsum/2q97 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2q97 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ACTS_RABIT ACTS_RABIT] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Many human pathogens exploit the actin cytoskeleton during infection, including Toxoplasma gondii, an apicomplexan parasite related to Plasmodium, the agent of malaria. One of the most abundantly expressed proteins of T. gondii is toxofilin, a monomeric actin-binding protein (ABP) involved in invasion. Toxofilin is found in rhoptry and presents an N-terminal signal sequence, consistent with its being secreted during invasion. We report the structure of toxofilin amino acids 69-196 in complex with the host mammalian actin. Toxofilin presents an extended conformation and interacts with an antiparallel actin dimer, in which one of the actins is related by crystal symmetry. Consistent with this observation, analytical ultracentrifugation analysis shows that toxofilin binds two actins in solution. Toxofilin folds into five consecutive helices, which form three relatively independent actin-binding sites. Helices 1 and 2 bind the symmetry-related actin molecule and cover its nucleotide-binding cleft. Helices 3-5 bind the other actin and constitute the primary actin-binding region. Helix 3 interacts in the cleft between subdomains 1 and 3, a common binding site for most ABPs. Helices 4 and 5 wrap around actin subdomain 4, and residue Gln-134 of helix 4 makes a hydrogen-bonding contact with the nucleotide in actin, both of which are unique features among ABPs. Toxofilin dramatically inhibits nucleotide exchange on two actin molecules simultaneously. This effect is linked to the formation of the antiparallel actin dimer because a construct lacking helices 1 and 2 binds only one actin and inhibits nucleotide exchange less potently.

Toxofilin from Toxoplasma gondii forms a ternary complex with an antiparallel actin dimer.,Lee SH, Hayes DB, Rebowski G, Tardieux I, Dominguez R Proc Natl Acad Sci U S A. 2007 Oct 9;104(41):16122-7. Epub 2007 Oct 2. PMID:17911258<ref>PMID:17911258</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2q97" style="background-color:#fffaf0;"></div>

==See Also==
*[[Actin 3D structures|Actin 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Oryctolagus cuniculus]]
[[Category: Toxoplasma gondii]]
[[Category: Dominguez R]]
[[Category: Lee SH]]