title: Structural similarity of a developmentally regulated bacterial spore coat protein to beta gamma-crystallins of the vertebrate eye lens.
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 S consists of four internally homologous motifs, arranged to produce two domains with a pseudo-twofold symmetry axis, overall resembling a triangular prism. Each domain consists of two topologically inequivalent "Greek keys": the second and fourth motifs form standard Greek keys, whereas the first and third motifs each contain a regular alpha-helix in addition to the usual four beta-strands. The structure of protein S is similar to those of the vertebrate eye lens beta gamma-crystallins, which are thought to be evolutionarily related to protein S. Both protein S and the beta gamma-crystallins function by forming stable multimolecular assemblies. However, protein S possesses distinctive motif organization and domain packing, indicating a different mode of oligomerization and a divergent evolutionary pathway from the beta gamma-crystallins.
authors.affiliation: Division of Molecular and Structural Biology, Ontario Cancer Institute, University of Toronto, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Bagby
authors.forename: T S
authors.initials: TS
authors.lastname: Harvey
authors.forename: S G
authors.initials: SG
authors.lastname: Eagle
authors.forename: S
authors.initials: S
authors.lastname: Inouye
authors.forename: M
authors.initials: M
authors.lastname: Ikura
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D003459:Crystallins / Q000737:chemistry*; D004926:Escherichia coli / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D016296:Mutagenesis; D016941:Myxococcus xanthus / Q000254:growth & development / Q000378:metabolism*; D017354:Point Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013171:Spores, Bacterial; D014714:Vertebrates; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D003459:Crystallins; C046032:Myxococcus spore coat proteins; D011994:Recombinant Proteins; D002118:Calcium