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==Structure of the human CR3 - CD11bCD18 specific nanobody hCR3Nb1== | ==Structure of the human CR3 - CD11bCD18 specific nanobody hCR3Nb1== | ||
<StructureSection load='7np9' size='340' side='right'caption='[[7np9]]' scene=''> | <StructureSection load='7np9' size='340' side='right'caption='[[7np9]], [[Resolution|resolution]] 1.14Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7NP9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7NP9 FirstGlance]. <br> | <table><tr><td colspan='2'>[[7np9]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Lama_glama Lama glama]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=7NP9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=7NP9 FirstGlance]. <br> | ||
</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=7np9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7np9 OCA], [https://pdbe.org/7np9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7np9 RCSB], [https://www.ebi.ac.uk/pdbsum/7np9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7np9 ProSAT]</span></td></tr> | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=7np9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=7np9 OCA], [https://pdbe.org/7np9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=7np9 RCSB], [https://www.ebi.ac.uk/pdbsum/7np9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=7np9 ProSAT]</span></td></tr> | |||
</table> | </table> | ||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
The integrin receptor alphaMbeta2 mediates phagocytosis of complement-opsonized objects, adhesion to the extracellular matrix, and transendothelial migration of leukocytes. However, the mechanistic aspects of alphaMbeta2 signaling upon ligand binding are unclear. Here, we present the first atomic structure of the human alphaMbeta2 headpiece fragment in complex with the nanobody (Nb) hCD11bNb1 at a resolution of 3.2 A. We show that the receptor headpiece adopts the closed conformation expected to exhibit low ligand affinity. The crystal structure indicates that in the R77H alphaM variant, associated with systemic lupus erythematosus, the modified allosteric relationship between ligand binding and integrin outside-inside signaling is due to subtle conformational effects transmitted over a distance of 40 A. Furthermore, we found the Nb binds to the alphaI domain of the alphaM subunit in an Mg(2+)-independent manner with low nanomolar affinity. Biochemical and biophysical experiments with purified proteins demonstrated that the Nb acts as a competitive inhibitor through steric hindrance exerted on the thioester domain of complement component iC3b attempting to bind the alphaM subunit. Surprisingly, we show that the Nb stimulates the interaction of cell-bound alphaMbeta2 with iC3b, suggesting that it may represent a novel high-affinity proteinaceous alphaMbeta2-specific agonist. Taken together, our data suggest that the iC3b-alphaMbeta2 complex may be more dynamic than predicted from the crystal structure of the core complex. We propose a model based on the conformational spectrum of the receptor to reconcile these observations regarding the functional consequences of hCD11bNb1 binding to alphaMbeta2. | |||
Structural insights into the function-modulating effects of nanobody binding to the integrin receptor alphaMbeta2.,Jensen RK, Pedersen H, Lorentzen J, Laursen NS, Vorup-Jensen T, Andersen GR J Biol Chem. 2022 Aug;298(8):102168. doi: 10.1016/j.jbc.2022.102168. Epub 2022, Jun 20. PMID:35738398<ref>PMID:35738398</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 7np9" style="background-color:#fffaf0;"></div> | |||
==See Also== | |||
*[[Antibody 3D structures|Antibody 3D structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
[[Category: Lama glama]] | |||
[[Category: Large Structures]] | [[Category: Large Structures]] | ||
[[Category: Andersen GR]] | [[Category: Andersen GR]] | ||
[[Category: Jensen RK]] | [[Category: Jensen RK]] | ||
Revision as of 09:36, 7 April 2023
Structure of the human CR3 - CD11bCD18 specific nanobody hCR3Nb1Structure of the human CR3 - CD11bCD18 specific nanobody hCR3Nb1
Structural highlights
Publication Abstract from PubMedThe integrin receptor alphaMbeta2 mediates phagocytosis of complement-opsonized objects, adhesion to the extracellular matrix, and transendothelial migration of leukocytes. However, the mechanistic aspects of alphaMbeta2 signaling upon ligand binding are unclear. Here, we present the first atomic structure of the human alphaMbeta2 headpiece fragment in complex with the nanobody (Nb) hCD11bNb1 at a resolution of 3.2 A. We show that the receptor headpiece adopts the closed conformation expected to exhibit low ligand affinity. The crystal structure indicates that in the R77H alphaM variant, associated with systemic lupus erythematosus, the modified allosteric relationship between ligand binding and integrin outside-inside signaling is due to subtle conformational effects transmitted over a distance of 40 A. Furthermore, we found the Nb binds to the alphaI domain of the alphaM subunit in an Mg(2+)-independent manner with low nanomolar affinity. Biochemical and biophysical experiments with purified proteins demonstrated that the Nb acts as a competitive inhibitor through steric hindrance exerted on the thioester domain of complement component iC3b attempting to bind the alphaM subunit. Surprisingly, we show that the Nb stimulates the interaction of cell-bound alphaMbeta2 with iC3b, suggesting that it may represent a novel high-affinity proteinaceous alphaMbeta2-specific agonist. Taken together, our data suggest that the iC3b-alphaMbeta2 complex may be more dynamic than predicted from the crystal structure of the core complex. We propose a model based on the conformational spectrum of the receptor to reconcile these observations regarding the functional consequences of hCD11bNb1 binding to alphaMbeta2. Structural insights into the function-modulating effects of nanobody binding to the integrin receptor alphaMbeta2.,Jensen RK, Pedersen H, Lorentzen J, Laursen NS, Vorup-Jensen T, Andersen GR J Biol Chem. 2022 Aug;298(8):102168. doi: 10.1016/j.jbc.2022.102168. Epub 2022, Jun 20. PMID:35738398[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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