Three-dimensional models corresponding to the C-terminal domain of human alphaA- and alphaB-crystallins based on the crystal structure of the small heat-shock protein HSP16.9 from wheat.
We propose three-dimensional models corresponding to the C-terminal domain of human alphaA- and alphaB-crystallins by using the comparative modeling program Modeler and the more closely related crystal structure of the small heat-shock protein (sHSP) belonging to the eukaryotic species from wheat HSP16.9 as template structure. The sequence alignments differ slightly from alignments that were used previously to construct alpha-crystallin models based on homology and the crystal structure of the more distantly related small heat-shock protein from archaeal species; Methanococcus jannaschii Mj HSP16.5, the only related structure then available as a template. The alpha-crystallin models based on HSP16.9 show better 3-D profile scores and reflect the relative shifts in the beta-strands corresponding to the beta-sandwich associated with the core C-terminal domain that is common to small heat-shock proteins and the alpha-crystallins. The loop between the equivalent beta5-beta7 strands corresponds to a region of seven amino acid residues deletion in alpha-crystallins and defines the new set of amino acid residues likely to be associated with a dimer interface. The models may be useful to examine sites of mutations that are known to affect chaperone-like activity and provide the structural basis for dimerization in alpha-crystallins.
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India. guru@ccmb.res.in
Kunchur
K
Guruprasad
Kavita
K
Kumari
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry; D019281:Dimerization; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D014908:Triticum / Q000737:chemistry*; D038202:alpha-Crystallin A Chain / Q000737:chemistry* / Q000235:genetics; D038203:alpha-Crystallin B Chain / Q000737:chemistry* / Q000235:genetics
D019843:Archaeal Proteins; C113795:HSP16.5 protein, Methanococcus jannaschii; C101303:HSP16.9 protein, Triticum aestivum; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D038202:alpha-Crystallin A Chain; D038203:alpha-Crystallin B Chain