title: Binding of Myomesin to Obscurin-Like-1 at the Muscle M-Band Provides a Strategy for Isoform-Specific Mechanical Protection.
abstract: The sarcomeric cytoskeleton is a network of modular proteins that integrate mechanical and signaling roles. Obscurin, or its homolog obscurin-like-1, bridges the giant ruler titin and the myosin crosslinker myomesin at the M-band. Yet, the molecular mechanisms underlying the physical obscurin(-like-1):myomesin connection, important for mechanical integrity of the M-band, remained elusive. Here, using a combination of structural, cellular, and single-molecule force spectroscopy techniques, we decode the architectural and functional determinants defining the obscurin(-like-1):myomesin complex. The crystal structure reveals a trans-complementation mechanism whereby an incomplete immunoglobulin-like domain assimilates an isoform-specific myomesin interdomain sequence. Crucially, this unconventional architecture provides mechanical stability up to forces of ∼135 pN. A cellular competition assay in neonatal rat cardiomyocytes validates the complex and provides the rationale for the isoform specificity of the interaction. Altogether, our results reveal a novel binding strategy in sarcomere assembly, which might have implications on muscle nanomechanics and overall M-band organization.
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pernigo
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Cardiovascular Division, King's College London BHF Centre of Research Excellence, London SE1 1UL, UK.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukuzawa
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Department of Physics, King's College London, London WC2R 2LS, UK.
authors.forename: Amy E M
authors.initials: AEM
authors.lastname: Beedle
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Cardiovascular Division, King's College London BHF Centre of Research Excellence, London SE1 1UL, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Holt
authors.affiliation: European Molecular Biology Laboratory, Grenoble Outstation, 38042 Grenoble, France; School of Chemical and Physical Sciences, Keele University, Keele, Staffordshire, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Round
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Department of Computer Science and Synthetic Biology Theme, Brunel University London, London UB8 3PH, UK.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pandini
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Department of Physics, King's College London, London WC2R 2LS, UK. Electronic address: sergi.garcia-manyes@kcl.ac.uk.
authors.forename: Sergi
authors.initials: S
authors.lastname: Garcia-Manyes
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK; Cardiovascular Division, King's College London BHF Centre of Research Excellence, London SE1 1UL, UK. Electronic address: mathias.gautel@kcl.ac.uk.
authors.forename: Mathias
authors.initials: M
authors.lastname: Gautel
authors.affiliation: Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK. Electronic address: roberto.steiner@kcl.ac.uk.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Steiner
mesh_terms: D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D064211:Connectin / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism; D008958:Models, Molecular; D018482:Muscle, Skeletal / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D017346:Protein Serine-Threonine Kinases; D051381:Rats; D064067:Rho Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000378:metabolism*; D012518:Sarcomeres / Q000378:metabolism
chemical_list: D064211:Connectin; D003598:Cytoskeletal Proteins; D007136:Immunoglobulins; C577299:MYOM1 protein, human; C522000:OBSL1 protein, human; D064067:Rho Guanine Nucleotide Exchange Factors; C578224:OBSCN protein, human; D017346:Protein Serine-Threonine Kinases
keywords: M-band; SAXS; X-ray crystallography; atomic force microscopy; immunoglobulin domain; muscle; myomesin; obscurin; obscurin-like-1; protein complexes