title: Structures of two repeats of spectrin suggest models of flexibility.
abstract: Spectrin is a vital component of the cytoskeleton, conferring flexibility on cells and providing a scaffold for a variety of proteins. It is composed of tandem, antiparallel coiled-coil repeats. We report four related crystal structures at 1.45 A, 2.0 A, 3.1 A, and 4.0 A resolution of two connected repeats of chicken brain alpha-spectrin. In all of the structures, the linker region between adjacent units is alpha-helical without breaks, kinks, or obvious boundaries. Two features observed in the structures are (1) conformational rearrangement in one repeat, resulting in movement of the position of a loop, and (2) varying degrees of bending at the linker region. These features form the basis of two different models of flexibility: a conformational rearrangement and a bending model. These models provide novel atomic details of spectrin flexibility.
authors.affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: V L
authors.initials: VL
authors.lastname: Grum
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: R I
authors.initials: RI
authors.lastname: MacDonald
authors.forename: A
authors.initials: A
authors.lastname: Mondragón
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001923:Brain Chemistry; D002645:Chickens; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009038:Motion; D009419:Nerve Tissue Proteins / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D020449:Repetitive Sequences, Amino Acid; D013049:Spectrin / Q000737:chemistry*
chemical_list: D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D013049:Spectrin