Structural similarity of a developmentally regulated bacterial spore coat protein to beta gamma-crystallins of the vertebrate eye lens

摘要: Abstract The solution structure of Ca(2+)-loaded protein S (M(r) 18,792) from the Gram-negative soil bacterium Myxococcus xanthus has been determined by multidimensional heteronuclear NMR spectroscopy. Protein consists four internally homologous motifs, arranged to produce two domains with a pseudo-twofold symmetry axis, overall resembling triangular prism. Each domain topologically inequivalent "Greek keys": second and fourth motifs form standard Greek keys, whereas first third each contain regular alpha-helix in addition usual beta-strands. The is similar those vertebrate eye lens beta gamma-crystallins, which are thought be evolutionarily related S. Both gamma-crystallins function forming stable multimolecular assemblies. However, possesses distinctive motif organization packing, indicating different mode oligomerization divergent evolutionary pathway gamma-crystallins.