Structure of severin domain 2 in solution.
The three-dimensional structure of domain 2 of severin in aqueous solution was determined by nuclear magnetic resonance spectroscopy. Severin is a Ca(2+)-activated actin-binding protein that servers F-actin, nucleates actin assembly, and caps the fast-growing ends of actin filaments. The 114-residue domain consists of a central five-stranded beta-sheet, sandwiched between a parallel four-turn alpha-helix and, on the other face, a roughly perpendicular two-turn alpha-helix. There are two distinct binding sites for Ca2+ located near the N and C termini of the long helix. Conserved residues of the gelsolin-severin family contribute to the apolar core of domain 2 of severin, so that the overall fold of the protein is similar to those of segment 1 of gelsolin and profilins. Together with biochemical experiments, this structure helps to explain how severin interacts with actin.
Schnuchel
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Max-Planck-Institute for Biochemistry, Martinsried, F.R.G.
Wiltscheck
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Eichinger
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Schleicher
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Holak
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D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000648:ultrastructure; D002645:Chickens; D003285:Contractile Proteins; D005656:Fungal Proteins / Q000737:chemistry* / Q000648:ultrastructure; D018260:Gelsolin / Q000737:chemistry / Q000648:ultrastructure; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008840:Microfilament Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051304:Profilins; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry
D000199:Actins; D002352:Carrier Proteins; D003285:Contractile Proteins; D005656:Fungal Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; C495738:PFN1 protein, human; D051304:Profilins; D015800:Protozoan Proteins; C036571:severin protein, Dictyostelium; C026615:villin