title: Chemical cross-linking indicates a staggered and antiparallel protofilament of desmin intermediate filaments and characterizes one higher-level complex between protofilaments.
abstract: Tetrameric rods, protofilaments and assembled filaments of desmin, the intermediate filament protein of muscle, have been chemically cross-linked with the lysine specific cross-linkers EGS [ethylene glycol bis(succinimidylsuccinate), 1.61 nm span] and bis(sulfosuccinimidyl) suberate (1.14 nm span). One bis(sulfosuccinimidyl)suberate and two EGS cross-links were isolated from the rod and characterized. They show that the two coiled coils in the rod tetramer are staggered by approximately 15-20 nm and strongly indicate an antiparallel arrangement in which the inner overlapping part of the rod is formed by the amino-terminal helices 1A, 1B and 2A. Both EGS cross-links identified in the rod were also isolated from cross-linked filaments. The isolated rod, therefore, represents a complex also present in identical, or very similar form in protofilaments and in assembled filaments. Cross-linked filaments yielded a third EGS cross-link that must have been formed between neighboring protofilaments. It connects the highly conserved carboxy-terminus of helix 2B of the first protofilament to the overlap region formed by helices 1A and 2A of the second protofilament. The restrictions posed by these cross-links on current filament models are discussed.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Department of Biochemistry, Göttingen, Federal Republic of Germany.
authors.forename: N
authors.initials: N
authors.lastname: Geisler
authors.forename: J
authors.initials: J
authors.lastname: Schünemann
authors.forename: K
authors.initials: K
authors.lastname: Weber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003432:Cross-Linking Reagents; D003488:Cyanogen Bromide; D003893:Desmin / Q000737:chemistry* / Q000648:ultrastructure; D005895:Gizzard, Avian / Q000737:chemistry; D007382:Intermediate Filaments / Q000648:ultrastructure*; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D012697:Serine Endopeptidases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D003893:Desmin; D046911:Macromolecular Substances; D010446:Peptide Fragments; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin; D003488:Cyanogen Bromide