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Søren Vrønning Hoffmann

Multiple low-affinity interactions support binding of human osteopontin to integrin αXβ2

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Multiple low-affinity interactions support binding of human osteopontin to integrin αXβ2. / Kläning, Eva; Christensen, Brian Søndergaard; Bajic, Goran; Hoffmann, Søren V; Jones, Nykola C; Callesen, Morten M; Andersen, Gregers Rom; Sørensen, Esben Skipper; Vorup-Jensen, Thomas.

In: B B A - Proteins and Proteomics, Vol. 1854, No. 8, 01.04.2015, p. 930-938.

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@article{154ec152655a4cd293370e48cd6ae58f,
title = "Multiple low-affinity interactions support binding of human osteopontin to integrin αXβ2",
abstract = "Integrin αXβ2 (also known as complement receptor 4, p150,95, or CD11c/CD18) is expressed in the cell membrane of myeloid leukocytes. αXβ2 has been reported to bind a large number of structurally unrelated ligands, often with a shared molecular character in the presence of polyanionic stretches in poorly folded proteins or glucosaminoglycans. Nevertheless, it is unclear what chemical sources of polyanionicity enable the binding by αXβ2. Osteopontin (OPN) is an intrinsically disordered protein, which facilitates phagocytosis via the integrin αXβ2. Unlike for other integrins, neither the RGD nor the SVVYGLR motifs account for this binding, and the molecular basis of OPN binding by αXβ2 remains uncharacterized. Here, we show that the monovalent interactions between the ligand-binding domain of αXβ2 and OPN, its fragments, or caseins are weak, with dissociation constants higher than 10(-5)M but with high apparent stoichiometries. From comparison with cell adhesion studies, the discrimination between αXβ2 ligands and non-ligands appears to rely on these apparent stoichiometries in a way, which involves glutamate rather than aspartate side chains. Surprisingly, the extensive, negatively charged phosphorylation of OPN is not contributing to αXβ2 binding. Furthermore, synchrotron radiation circular spectroscopy excludes that the phosphorylation affects the general folding of OPN. Taken together, our quantitative analyses reveal a mode of ligand recognition by integrin αXβ2, which seem to differ in principles considerably from other OPN receptors.",
author = "Eva Kl{\"a}ning and Christensen, {Brian S{\o}ndergaard} and Goran Bajic and Hoffmann, {S{\o}ren V} and Jones, {Nykola C} and Callesen, {Morten M} and Andersen, {Gregers Rom} and S{\o}rensen, {Esben Skipper} and Thomas Vorup-Jensen",
note = "Copyright {\textcopyright} 2015 Elsevier B.V. All rights reserved.",
year = "2015",
month = apr,
day = "1",
doi = "10.1016/j.bbapap.2015.03.008",
language = "English",
volume = "1854",
pages = "930--938",
journal = "B B A - Proteins and Proteomics",
issn = "1570-9639",
publisher = "Elsevier BV",
number = "8",

}

RIS

TY - JOUR

T1 - Multiple low-affinity interactions support binding of human osteopontin to integrin αXβ2

AU - Kläning, Eva

AU - Christensen, Brian Søndergaard

AU - Bajic, Goran

AU - Hoffmann, Søren V

AU - Jones, Nykola C

AU - Callesen, Morten M

AU - Andersen, Gregers Rom

AU - Sørensen, Esben Skipper

AU - Vorup-Jensen, Thomas

N1 - Copyright © 2015 Elsevier B.V. All rights reserved.

PY - 2015/4/1

Y1 - 2015/4/1

N2 - Integrin αXβ2 (also known as complement receptor 4, p150,95, or CD11c/CD18) is expressed in the cell membrane of myeloid leukocytes. αXβ2 has been reported to bind a large number of structurally unrelated ligands, often with a shared molecular character in the presence of polyanionic stretches in poorly folded proteins or glucosaminoglycans. Nevertheless, it is unclear what chemical sources of polyanionicity enable the binding by αXβ2. Osteopontin (OPN) is an intrinsically disordered protein, which facilitates phagocytosis via the integrin αXβ2. Unlike for other integrins, neither the RGD nor the SVVYGLR motifs account for this binding, and the molecular basis of OPN binding by αXβ2 remains uncharacterized. Here, we show that the monovalent interactions between the ligand-binding domain of αXβ2 and OPN, its fragments, or caseins are weak, with dissociation constants higher than 10(-5)M but with high apparent stoichiometries. From comparison with cell adhesion studies, the discrimination between αXβ2 ligands and non-ligands appears to rely on these apparent stoichiometries in a way, which involves glutamate rather than aspartate side chains. Surprisingly, the extensive, negatively charged phosphorylation of OPN is not contributing to αXβ2 binding. Furthermore, synchrotron radiation circular spectroscopy excludes that the phosphorylation affects the general folding of OPN. Taken together, our quantitative analyses reveal a mode of ligand recognition by integrin αXβ2, which seem to differ in principles considerably from other OPN receptors.

AB - Integrin αXβ2 (also known as complement receptor 4, p150,95, or CD11c/CD18) is expressed in the cell membrane of myeloid leukocytes. αXβ2 has been reported to bind a large number of structurally unrelated ligands, often with a shared molecular character in the presence of polyanionic stretches in poorly folded proteins or glucosaminoglycans. Nevertheless, it is unclear what chemical sources of polyanionicity enable the binding by αXβ2. Osteopontin (OPN) is an intrinsically disordered protein, which facilitates phagocytosis via the integrin αXβ2. Unlike for other integrins, neither the RGD nor the SVVYGLR motifs account for this binding, and the molecular basis of OPN binding by αXβ2 remains uncharacterized. Here, we show that the monovalent interactions between the ligand-binding domain of αXβ2 and OPN, its fragments, or caseins are weak, with dissociation constants higher than 10(-5)M but with high apparent stoichiometries. From comparison with cell adhesion studies, the discrimination between αXβ2 ligands and non-ligands appears to rely on these apparent stoichiometries in a way, which involves glutamate rather than aspartate side chains. Surprisingly, the extensive, negatively charged phosphorylation of OPN is not contributing to αXβ2 binding. Furthermore, synchrotron radiation circular spectroscopy excludes that the phosphorylation affects the general folding of OPN. Taken together, our quantitative analyses reveal a mode of ligand recognition by integrin αXβ2, which seem to differ in principles considerably from other OPN receptors.

U2 - 10.1016/j.bbapap.2015.03.008

DO - 10.1016/j.bbapap.2015.03.008

M3 - Journal article

C2 - 25839998

VL - 1854

SP - 930

EP - 938

JO - B B A - Proteins and Proteomics

JF - B B A - Proteins and Proteomics

SN - 1570-9639

IS - 8

ER -