Structural principles for the propeller assembly of beta-sheets: the preference for seven-fold symmetry.
Twisted beta-sheets, packed face to face, may be arranged in circular formation like blades of a propeller or turbine. This beta-propeller fold has been found in three proteins: that in neuraminidase consists of six beta-sheets while those in methylamine dehydrogenase and galactose oxidase are composed of seven beta-sheets. A model for multisheet packing in the beta-propeller fold is proposed. This model gives both geometrical parameters of the beta-propellers composed of different numbers of sheets and patterns of residue packing at their sheet-to-sheet interfaces. All the known beta-propeller structures have been analyzed, and the observed geometries and residue packing are found to be in good agreement with those predicted by models. It is shown that unusual seven-fold symmetry is preferable to six- or eight-fold symmetry for propeller-like multi-sheet assembly. According to the model, a six-beta-sheet propeller has to have predominantly small residues in the beta-strands closed to its six-fold axis, but no strong sequence constraints are necessary for a seven-fold beta-propeller.
Murzin
A G
AG
MRC Laboratory of Molecular Biology, Cambridge, England.
D005692:Galactose Oxidase / Q000737:chemistry; D008958:Models, Molecular; D009439:Neuraminidase / Q000737:chemistry; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry; D017433:Protein Structure, Secondary
D005692:Galactose Oxidase; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors; D009439:Neuraminidase