2JJZ

Crystal Structure of Human Iba2, orthorhombic crystal form

Summary for 2JJZ

• Entry DOI: 10.2210/pdb2jjz/pdb
• Related: 2VTG
• Descriptor: IONIZED CALCIUM-BINDING ADAPTER MOLECULE 2, ZINC ION, ACETATE ION, ... (7 entities in total)
• Functional Keywords: ef-hand, calcium binding, actin crosslinking, ionized calcium binding adapter molecule 2, metal-binding protein, metal binding protein
• Biological source: HOMO SAPIENS (HUMAN); More
• Cellular location: Cytoplasm, cytoskeleton: Q9BQI0 Q9BQI0
• Total number of polymer chains: 4
• Total formula weight: 68844.97

Authors

Schulze, J.O.,Quedenau, C.,Roske, Y.,Turnbull, A.,Mueller, U.,Heinemann, U.,Buessow, K. (deposition date: 2008-05-15, release date: 2009-07-14, Last modification date: 2023-12-13)

Primary citation

Schulze, J.O.,Quedenau, C.,Roske, Y.,Adam, T.,Schuler, H.,Behlke, J.,Turnbull, A.P.,Sievert, V.,Scheich, C.,Mueller, U.,Heinemann, U.,Bussow, K.
Structural and Functional Characterization of Human Iba Proteins.
FEBS J., 275:4627-, 2008

PubMed Abstract: Iba2 is a homolog of ionized calcium-binding adapter molecule 1 (Iba1), a 17-kDa protein that binds and cross-links filamentous actin (F-actin) and localizes to membrane ruffles and phagocytic cups. Here, we present the crystal structure of human Iba2 and its homodimerization properties, F-actin cross-linking activity, cellular localization and recruitment upon bacterial invasion in comparison with Iba1. The Iba2 structure comprises two central EF-hand motifs lacking bound Ca2+. Iba2 crystallized as a homodimer stabilized by a disulfide bridge and zinc ions. Analytical ultracentrifugation revealed a different mode of dimerization under reducing conditions that was independent of Ca2+. Furthermore, no binding of Ca2+ up to 0.1 mM was detected by equilibrium dialysis. Correspondingly, Iba EF-hand motifs lack residues essential for strong Ca2+ coordination. Sedimentation experiments and microscopy detected pronounced, indistinguishable F-actin binding and cross-linking activity of Iba1 and Iba2 with induction of F-actin bundles. Fluorescent Iba fusion proteins were expressed in HeLa cells and co-localized with F-actin. Iba1 was recruited into cellular projections to a larger extent than Iba2. Additionally, we studied Iba recruitment in a Shigella invasion model that induces cytoskeletal rearrangements. Both proteins were recruited into the bacterial invasion zone and Iba1 was again concentrated slightly higher in the cellular extensions.

PubMed: 18699778
DOI: 10.1111/J.1742-4658.2008.06605.X

Experimental method

X-RAY DIFFRACTION (2.15 Å)