title: A molecular ruler regulates cytoskeletal remodelling by the Rho kinases.
abstract: The Rho-associated coiled-coil kinases (ROCK) are essential regulators of the actin cytoskeleton; however, the structure of a full-length ROCK is unknown and the mechanisms by which its kinase activity is controlled are not well understood. Here we determine the low-resolution structure of human ROCK2 using electron microscopy, revealing it to be a constitutive dimer, 120 nm in length, with a long coiled-coil tether linking the kinase and membrane-binding domains. We find, in contrast to previous reports, that ROCK2 activity does not appear to be directly regulated by binding to membranes, RhoA, or by phosphorylation. Instead, we show that changing the length of the tether modulates ROCK2 function in cells, suggesting that it acts as a molecular ruler. We present a model in which ROCK activity is restricted to a discrete region of the actin cytoskeleton, governed by the length of its coiled-coil. This represents a new type of spatial control, and hence a new paradigm for kinase regulation.
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, Vienna Biocenter, 1030 Vienna, Austria.
authors.forename: Linda
authors.initials: L
authors.lastname: Truebestein
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, Vienna Biocenter, 1030 Vienna, Austria.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Elsner
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, Vienna Biocenter, 1030 Vienna, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fuchs
authors.affiliation: Department of Structural and Computational Biology, Max F. Perutz Laboratories, Vienna Biocenter, 1030 Vienna, Austria.|Department of Medical Biochemistry, Medical University of Vienna, 1090 Vienna, Austria.
authors.forename: Thomas A
authors.identifier: http://orcid.org/0000-0001-6853-666X
authors.initials: TA
authors.lastname: Leonard
mesh_terms: D000199:Actins / Q000378:metabolism; D003599:Cytoskeleton / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D017434:Protein Structure, Tertiary; D054460:rho-Associated Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; C515852:ROCK2 protein, human; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein