title: The zipper groups of the amyloid state of proteins.
abstract: Fibrous proteins in the amyloid state are found both associated with numerous diseases and in the normal functions of cells. Amyloid fibers contain a repetitive spine, commonly built from a pair of β-sheets whose β-strands run perpendicular to the fiber direction and whose side chains interdigitate, much like the teeth of a zipper. In fiber spines known as homosteric zippers, identical protein segments sharing identical packing environments make the two β-sheets. In previous work based on atomic resolution crystal structures of homosteric zippers derived from a dozen proteins, the symmetries of homosteric zippers were categorized into eight classes. Here, it is shown through a formal derivation that each homosteric zipper class corresponds to a unique set of symmetry groups termed `zipper groups'. Furthermore, the eight previously identified classes do not account for all of the 15 possible zipper groups, which may be categorized into the complete set of ten classes. Because of their foundations in group theory, the 15 zipper groups provide a mathematically rigorous classification for homosteric zippers.
authors.affiliation: Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, UCLA-DOE Institute for Genomics and Proteomics, University of California at Los Angeles, Los Angeles, CA 90095-1570, USA. jstroud@mbi.ucla.edu
authors.forename: James C
authors.initials: JC
authors.lastname: Stroud
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000145:classification; D058227:Amyloidogenic Proteins / Q000737:chemistry* / Q000145:classification*; D018360:Crystallography, X-Ray; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013237:Stereoisomerism; D009626:Terminology as Topic
chemical_list: D016564:Amyloid beta-Protein Precursor; D058227:Amyloidogenic Proteins
keywords: amyloid fibers; amyloid spine; group theory; steric zippers; symmetry; zipper groups