S100A6 and S100A11 are specific targets of the calcium- and zinc-binding S100B protein in vivo.
In solution, S100B protein is a noncovalent homodimer composed of two subunits associated in an antiparallel manner. Upon calcium binding, the conformation of S100B changes dramatically, leading to the exposure of hydrophobic residues at the surface of S100B. The residues in the C-terminal domain of S100B encompassing Phe(87) and Phe(88) have been implicated in interaction with target proteins. In this study, we used two-hybrid technology to identify specific S100B target proteins. Using S100B as bait, we identify S100A6 and S100A11 as specific targets for S100B. S100A1, the closest homologue of S100B, is capable of interaction with S100B but does not interact with S100A6 or S100A11. S100B, S100A6, and S100A11 isoforms are co-regulated and co-localized in astrocytoma U373 cells. Furthermore, co-immunoprecipitation experiments demonstrated that Ca(2+)/Zn(2+) stabilizes S100B-S100A6 and S100B-S100A11 heterocomplexes. Deletion of the C-terminal domain or mutation of Phe(87) and Phe(88) residues has no effect on S100B homodimerization and heterodimerization with S100A1 but drastically decreases interaction between S100B and S100A6 or S100A11. Our data suggest that the interaction between S100B and S100A6 or S100A11 should not be viewed as a typical S100 heterodimerization but rather as a model of interaction between S100B and target proteins.
Deloulme
J C
JC
Département de Biologie Moléculaire et Structurale du Commissariat à l'Energie Atomique, INSERM Unité 244, Commissariat à l'Energie Atomique-Grenoble, 38054 Grenoble Cedex 9, France. jcdeloulme@cea.fr
Assard
N
N
Mbele
G O
GO
Mangin
C
C
Kuwano
R
R
Baudier
J
J
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001254:Astrocytoma / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D018797:Cell Cycle Proteins; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D005656:Fungal Proteins / Q000378:metabolism; D017353:Gene Deletion; D015723:Gene Library; D006801:Humans; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009414:Nerve Growth Factors / Q000737:chemistry / Q000378:metabolism*; D010649:Phenylalanine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D000075383:S100 Calcium Binding Protein A6; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D015032:Zinc / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D005656:Fungal Proteins; D009414:Nerve Growth Factors; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D000075383:S100 Calcium Binding Protein A6; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579160:S100B protein, human; C055351:S100A6 protein, human; C072337:S100A11 protein, human; D010649:Phenylalanine; D001616:beta-Galactosidase; D015032:Zinc; D002118:Calcium