2FH2

C-terminal half of gelsolin soaked in EGTA at pH 4.5

Summary for 2FH2

• Entry DOI: 10.2210/pdb2fh2/pdb
• Related: 2FH1 2FH3 2FH4
• Descriptor: Gelsolin, CALCIUM ION (3 entities in total)
• Functional Keywords: gelsolin, egta, contractile protein
• Biological source: Homo sapiens (human)
• Cellular location: Isoform 2: Cytoplasm, cytoskeleton. Isoform 1: Secreted: P06396
• Total number of polymer chains: 3
• Total formula weight: 113606.92

Authors

Chumnarnsilpa, S.,Loonchanta, A.,Xue, B.,Choe, H.,Urosev, D.,Wang, H.,Burtnick, L.D.,Robinson, R.C. (deposition date: 2005-12-23, release date: 2006-06-13, Last modification date: 2024-03-13)

Primary citation

Chumnarnsilpa, S.,Loonchanta, A.,Xue, B.,Choe, H.,Urosev, D.,Wang, H.,Lindberg, U.,Burtnick, L.D.,Robinson, R.C.
Calcium ion exchange in crystalline gelsolin
J.Mol.Biol., 357:773-782, 2006

PubMed Abstract: Gelsolin is a calcium and pH-sensitive modulator of actin filament length. Here, we use X-ray crystallography to examine the extraction and exchange of calcium ions from their binding sites in different crystalline forms of the activated N and C-terminal halves of gelsolin, G1-G3 and G4-G6, respectively. We demonstrate that the combination of calcium and low pH activating conditions do not induce conformational changes in G4-G6 beyond those elicited by calcium alone. EGTA is able to remove calcium ions bound to the type I and type II metal ion-binding sites in G4-G6. Constrained by crystal contacts and stabilized by interdomain interaction surfaces, the gross structure of calcium-depleted G4-G6 remains that of the activated form. However, high-resolution details of changes in the ion-binding sites may represent the initial steps toward restoration of the arrangement of domains found in the calcium-free inactive form of gelsolin in solution. Furthermore, bathing crystals with the trivalent calcium ion mimic, Tb3+, results in anomalous scattering data that permit unequivocal localization of terbium ions in each of the proposed type I and type II ion-binding sites of both halves of gelsolin. In contrast to predictions based on solution studies, we find that no calcium ion is immune to exchange.

PubMed: 16466744
DOI: 10.1016/j.jmb.2006.01.026

Experimental method

X-RAY DIFFRACTION (2.5 Å)