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The high‐molecular‐weight kininogen Domain 5 is an intrinsically unstructured protein and its interaction with ferritin is metal mediated
Author(s) -
Huhn Annissa J.,
Parsonage Derek,
Horita David A.,
Torti Frank M.,
Torti Suzy V.,
Hollis Thomas
Publication year - 2014
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.2486
Subject(s) - high molecular weight kininogen , ferritin , protein–protein interaction , chemistry , domain (mathematical analysis) , microbiology and biotechnology , biochemistry , biology , kininogen , receptor , bradykinin , mathematical analysis , mathematics
High‐molecular‐weight kininogen domain 5 (HK5) is an angiogenic modulator that is capable of inhibiting endothelial cell proliferation, migration, adhesion, and tube formation. Ferritin can bind to a histidine–glycine–lysine‐rich region within HK5 and block its antiangiogenic effects. However, the molecular intricacies of this interaction are not well understood. Analysis of the structure of HK5 using circular dichroism and nuclear magnetic resonance [ 1 H, 15 N]‐heteronuclear single quantum coherence determined that HK5 is an intrinsically unstructured protein, consistent with secondary structure predictions. Equilibrium binding studies using fluorescence anisotropy were used to study the interaction between ferritin and HK5. The interaction between the two proteins is mediated by metal ions such as Co 2+ , Cd 2+ , and Fe 2+ . This metal‐mediated interaction works independently of the loaded ferrihydrite core of ferritin and is demonstrated to be a surface interaction. Ferritin H and L bind to HK5 with similar affinity in the presence of metals. The ferritin interaction with HK5 is the first biological function shown to occur on the surface of ferritin using its surface‐bound metals.