title: Large-scale modelling of the divergent spectrin repeats in nesprins: giant modular proteins.
abstract: Nesprin-1 and nesprin-2 are nuclear envelope (NE) proteins characterized by a common structure of an SR (spectrin repeat) rod domain and a C-terminal transmembrane KASH [Klarsicht-ANC-Syne-homology] domain and display N-terminal actin-binding CH (calponin homology) domains. Mutations in these proteins have been described in Emery-Dreifuss muscular dystrophy and attributed to disruptions of interactions at the NE with nesprins binding partners, lamin A/C and emerin. Evolutionary analysis of the rod domains of the nesprins has shown that they are almost entirely composed of unbroken SR-like structures. We present a bioinformatical approach to accurate definition of the boundaries of each SR by comparison with canonical SR structures, allowing for a large-scale homology modelling of the 74 nesprin-1 and 56 nesprin-2 SRs. The exposed and evolutionary conserved residues identify important pbs for protein-protein interactions that can guide tailored binding experiments. Most importantly, the bioinformatics analyses and the 3D models have been central to the design of selected constructs for protein expression. 1D NMR and CD spectra have been performed of the expressed SRs, showing a folded, stable, high content α-helical structure, typical of SRs. Molecular Dynamics simulations have been performed to study the structural and elastic properties of consecutive SRs, revealing insights in the mechanical properties adopted by these modules in the cell.
authors.affiliation: Randall Division of Cell and Molecular Biophysics, School of Physical Sciences and Engineering, King's College London, London, United Kingdom.
authors.forename: Flavia
authors.initials: F
authors.lastname: Autore
authors.forename: Mark
authors.initials: M
authors.lastname: Pfuhl
authors.forename: Xueping
authors.initials: X
authors.lastname: Quan
authors.forename: Aisling
authors.initials: A
authors.lastname: Williams
authors.forename: Roland G
authors.initials: RG
authors.lastname: Roberts
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Shanahan
authors.forename: Franca
authors.initials: F
authors.lastname: Fraternali
mesh_terms: D000595:Amino Acid Sequence; D016384:Consensus Sequence; D003598:Cytoskeletal Proteins; D019143:Evolution, Molecular; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry*; D009687:Nuclear Proteins / Q000737:chemistry*; D025341:Principal Component Analysis; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid; D020539:Sequence Analysis, Protein; D013049:Spectrin / Q000737:chemistry
chemical_list: D003598:Cytoskeletal Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C415465:SYNE1 protein, human; C485904:SYNE2 protein, human; D013049:Spectrin