S100 proteins structure

J. Baudier and D. Gerard, Ions binding to S100 proteins Structural changes induced by calcium and zinc on SlOOa and SlOOb proteins, Biochemistry 22, 3360-3369 (1983). 

S100 proteins (named because of their solubility in a 100% ammonium sulfate solution) constitute the largest family within the EF-hand Ca2+-binding proteins superfamily [1]. SI00 proteins are small, acidic proteins containing two distinct Ca2+-binding EF-hand structural motifs [2]. The C-terminal EF-hand contains the... 

Structural analyses have revealed a typical architecture of the S100 proteins. Each S100 protein is composed of two EF-hand Ca2+-binding domains connected by a central hinge region (Fritz and Heizmann, 2004 Bhattacharya et al., 2004 ... 

Recently, the structure of the Zn2+-bound S100A2 was characterised in more detail (Koch et al, submitted). The binding of Zn2+ leads to the formation of a novel tetrameric structure different from other S100 proteins. This finding implies that, under physiological conditions, Zn2+ may control the cellular activity of S100A2. 

The crystal structure of S100A7 revealed that this protein, in contrast to other S100 proteins, probably binds only one calcium ion per monomer and this binding does not induce large conformational changes of the protein (Boeshans et al 2006 Brodersen et al 1998). 

Brodersen DE, Nyborg J, Kjeldgaard M. 1999. Zinc-binding site of an S100 protein revealed. Two crystal structures of Ca2+-bound human psoriasin (S100A7) in the Zn2+-loaded and Zn2+-free states. Biochemistry 38(6) 1695-1704. 

Fritz G, Heizmann CW. 2004. 3D-structures of the Ca2+- and Zn2+-binding S100 proteins. A. Messer-schmidt WB, M. Cygler, eds., editor. Chichester John Wiley Sons. p. 529-540. 

Otterbein LR, Kordowska J, Witte-Hoffmann C, Wang CL, Dominguez R. 2002. Crystal structures of S100A6 in the Ca(2+)-free and Ca(2+)-bound states the calcium sensor mechanism of S100 proteins revealed at atomic resolution. Structure 10(4) 557-567. 

Sivaraja V, Kumar TK, Prudovsky I, Yu C. 2005. Three-dimensional solution structure of a unique S100 protein. Biochem Biophys Res Commun 335(4) 1140-1148. 

CBD is the smallest EF-hand protein with two EF-hand motifs. As a member of the S100 protein family, CBD contains one canonical and one pseudo-EF-hand motif at the C-terminus and N-terminus of the protein, respectively (Figure 11). Unlike other SI00 proteins, CBD remains monomeric in solution. Chazin and Forsen s groups have carried out extensive structural studies of CBD at different conditions. Tike parvalbumin, no significant stracture changes have been observed upon calcium binding. ... 

The S100 proteins make up a distinct subfamily within the EF-hand family. They share structural characteristics of being small... 

The structures also revealed a Zn2+-binding site in the protein. The coordination of the zinc ion is similar to the pattern seen in certain metalloproteases (Brodersen et al 1999). Sequence comparison suggests that this zinc-binding site is present in a number of the remaining members of the S100 family (Fritz and Heizmann, 2004). The structure of S100A7, crystallised in the absence of zinc, further showed that loss of zinc resulted in a reorganisation of the adjacent empty and distorted EF-hand loop, similarly to a calcium-loaded EF-hand. 

Potts BC, Smith J, Akke M, Macke TJ, Okazaki K, Hidaka H, Case DA, Chazin WJ. 1995. The structure of calcyclin reveals a novel homodimeric fold for S100 Ca(2+)-binding proteins. Nat Struct Biol 2(9) 790-796. 

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