1mho

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THE 2.0 A STRUCTURE OF HOLO S100B FROM BOVINE BRAIN

Overview

BACKGROUND. S100B (S100beta) is a member of the S100 family of small, calcium-binding proteins: members of this family contain two, helix-loop-helix calcium-binding motifs and interact with a wide range of, proteins involved mainly in the cytoskeleton and cell proliferation. S100B, is a neurite-extension factor and levels of S100B are elevated in the, brains of patients with Alzheimer's disease or Down's syndrome: the, pattern of S100B overexpression in Alzheimer's disease correlates with the, pattern of neuritic-plaque formation. Identification of a growing class of, S100 proteins and the likely neurochemical importance of S100B make the, determination of the structure of S100B of interest. RESULTS. We have used, NMR to determine the structure of the reduced S100B homodimer in the, absence of calcium. Each monomer consists of a four-helix bundle, arranged, in the dimer in an antiparallel fashion. The fourth helix of each monomer, runs close to the equivalent helix of the other monomer for almost its, full length, extending the hydrophobic core through the interface. The, N-terminal, but not the C-terminal, calcium-binding loop is similar to the, equivalent loop in the monomeric S100 protein calbindin and is in a, conformation ready to bind calcium. CONCLUSIONS. The novel dimer structure, reported previously for calcyclin (S100A6) is the common fold for the, dimeric S100B proteins. Calcium binding to the C-terminal calcium-binding, loop would be expected to require a conformational change, which might, provide a signal for activation. The structure suggests regions of the, molecule likely to be involved in interactions with effector molecules.

About this Structure

1MHO is a Single protein structure of sequence from Bos taurus with CA as ligand. Full crystallographic information is available from OCA.

Reference

The solution structure of the bovine S100B protein dimer in the calcium-free state., Kilby PM, Van Eldik LJ, Roberts GC, Structure. 1996 Sep 15;4(9):1041-52. PMID:8805590

Page seeded by OCA on Tue Nov 20 21:25:24 2007