Spore coat protein S is from the Gram-negative bacterial organism Myxococcus xanthus. It is a calcium (Ca2+)-binding protein that binds 2 calcium ions (shown in silver). During fruiting body formation, protein S forms many protective layers on the surface of myxospores in the presence of calcium. It is thought that this may also act as a cell-cell adhesive.
Structurally, protein S is very similar to vertebrate lens beta gamma-crystallins. Both of these types of proteins function by creating multimolecular assemblies. Protein S is made up of 4 internally homologous motifs which form 2 domains. Each domain consists of 2 Greek keys. Overall, the protein looks like a triangular prism. Protein S is 173 amino acid residues long. It consists of 15 beta strands, 2 alpha helices (magenta), and 2 310 helices (gold).

• Keywords: Calcium-Binding, Duplication, Sporulation
  
• View this protein's PDB entry as 1PRS
• View this protein's SwissProt entry as DESS_MYXXA
• References:
  • S. Bagby, T.S. Harvey, S.G. Eagle, S. Inouye, M. Ikura
    NMR-Derived Three-Dimensional Solution Structure of Protein S Complexed With Calcium.
    Structure 2:107 (1994)
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  • S. Bagby, T.S. Harvey, S.G. Eagle, S. Inouye, M. Ikura
    Structural Similarity of a Developmentally Regulated Bacterial Spore Coat Protein to Beta Gamma-Crystallins of the Vertebrate Eye Lens.
    Proc. Nat. Acad. Sci. USA 91:4308 (1994)
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  • S. Bagby, T.S. Harvey, L.E. Kay, S.G. Eagle, S. Inouye, M. Ikura
    Unusual Helix-Containing Greek Keys in Development-Specific Ca2+-Binding Protein S. 1H, 15N, and 13C Assignments and Secondary Structure Determined Using Multidimensional Double and Triple Resonance Heteronuclear NMR Spectroscopy.
    Biochemistry 33:2409 (1994)
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