title: Structure of the Intermediate Filament-Binding Region of Desmoplakin.
abstract: Desmoplakin (DP) is a cytoskeletal linker protein that connects the desmosomal cadherin/plakoglobin/plakophilin complex to intermediate filaments (IFs). The C-terminal region of DP (DPCT) mediates IF binding, and contains three plakin repeat domains (PRDs), termed PRD-A, PRD-B and PRD-C. Previous crystal structures of PRDs B and C revealed that each is formed by 4.5 copies of a plakin repeat (PR) and has a conserved positively charged groove on its surface. Although PRDs A and B are linked by just four amino acids, B and C are separated by a 154 residue flexible linker, which has hindered crystallographic analysis of the full DPCT. Here we present the crystal structure of a DPCT fragment spanning PRDs A and B, and elucidate the overall architecture of DPCT by small angle X-ray scattering (SAXS) analysis. The structure of PRD-A is similar to that of PRD-B, and the two domains are arranged in a quasi-linear arrangement, and separated by a 4 amino acid linker. Analysis of the B-C linker region using secondary structure prediction and the crystal structure of a homologous linker from the cytolinker periplakin suggests that the N-terminal ~100 amino acids of the linker form two PR-like motifs. SAXS analysis of DPCT indicates an elongated but non-linear shape with Rg = 51.5 Å and Dmax = 178 Å. These data provide the first structural insights into an IF binding protein containing multiple PRDs and provide a foundation for studying the molecular basis of DP-IF interactions.
authors.affiliation: Dept. of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Hyunook
authors.initials: H
authors.lastname: Kang
authors.affiliation: SLAC National Laboratory, Menlo Park, California, United States of America.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Weiss
authors.affiliation: Dept. of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Injin
authors.initials: I
authors.lastname: Bang
authors.affiliation: Depts. of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: William I
authors.initials: WI
authors.lastname: Weis
authors.affiliation: Dept. of Biological Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D051180:Desmoplakins / Q000737:chemistry / Q000378:metabolism*; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D051180:Desmoplakins; D007381:Intermediate Filament Proteins