The spectrin repeat folds into a three-helix bundle in solution.
Spectrin, a major component of the membrane skeleton, is mainly composed of tandemly repeated segments of approx. 106 amino acids. We have undertaken the determination of the three-dimensional structure of a chicken brain alpha-spectrin repeat by heteronuclear multidimensional NMR. Sedimentation equilibrium demonstrates that this repeat is monomeric at the concentration used for NMR (1 mM). Its secondary structure was identified using a collection of sequential and medium range NOEs, chemical shifts, HN-Halpha coupling constants, and relaxation measurements. These data unequivocally demonstrate the presence of three long helices connected by two loops. A set of interhelical NOEs indicates that the helices assemble into a triple helical structure. Our results provide experimental evidence supporting the triple-helical bundle proposed by modelling.
Pascual
J
J
European Molecular Biology Laboratory, Heidelberg, Germany.
Pfuhl
M
M
Rivas
G
G
Pastore
A
A
Saraste
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008961:Models, Structural; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013049:Spectrin / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification
D011994:Recombinant Proteins; D013049:Spectrin