PDBsum entry 1nsh

Metal binding protein

PDB id: 1nsh

Contents

Protein chains

101 a.a. *

* Residue conservation analysis

References listed in PDB file

Key reference

• Title: Unmasking the annexin i interaction from the structure of apo-S100a11.
• Authors: A.C.Dempsey, M.P.Walsh, G.S.Shaw.
• Ref.: Structure, 2003, 11, 887-897. [DOI no: 10.1016/S0969-2126(03)00126-6]
• PubMed id: 12842051

Abstract

S100A11 is a homodimeric EF-hand calcium binding protein that undergoes a calcium-induced conformational change and interacts with the phospholipid binding protein annexin I to coordinate membrane association. In this work, the solution structure of apo-S100A11 has been determined by NMR spectroscopy to uncover the details of its calcium-induced structural change. Apo-S100A11 forms a tight globular structure having a near antiparallel orientation of helices III and IV in calcium binding site II. Further, helices I and IV, and I and I', form a more closed arrangement than observed in other apo-S100 proteins. This helix arrangement in apo-S100A11 partially buries residues in helices I (P3, E11, A15), III (V55, R58, M59), and IV (A86, C87, S90) and the linker (A45, F46), which are required for interaction with annexin I in the calcium-bound state. In apo-S100A11, this results in a "masked" binding surface that prevents annexin I binding but is uncovered upon calcium binding.

Figure 6.
Figure 6. Formation of the Annexin I Binding Surface from Calcium Binding to Apo-S100A11Accessible surface area representations of apo-S100A11 (A) and calcium-bound S100A11 (B) in complex with annexin I (Rety et al., 2000). Each protein is oriented approximately 90° with respect to that shown in Figure 4. In both molecules, residues in S100A11 that directly interact (<5 Å) with annexin I are indicated and colored dark blue and those whose side chain exposure increases by >20% upon calcium binding but have less interaction are colored cyan. For apo-S100A11 (A), many of these residues have less than 20% of their side chains accessible to the surface and are disjoint on the surface of the protein. In the calcium-bound structure (B), most residues that contact the annexin I peptide increase their side chain-accessible surface areas by >20% as shown in Figure 5C to form a contiguous site for the annexin interaction (dark blue). To facilitate comparison, all sequence numbers correspond to those of rabbit S100A11.

The above figure is reprinted by permission from Cell Press: Structure (2003, 11, 887-897) copyright 2003.