Spore Coat Protein S

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).


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