title: Interfacial binding and aggregation of lamin A tail domains associated with Hutchinson-Gilford progeria syndrome.
abstract: Hutchinson-Gilford progeria syndrome is a premature aging disorder associated with the expression of ∆50 lamin A (∆50LA), a mutant form of the nuclear structural protein lamin A (LA). ∆50LA is missing 50 amino acids from the tail domain and retains a C-terminal farnesyl group that is cleaved from the wild-type LA. Many of the cellular pathologies of HGPS are thought to be a consequence of protein-membrane association mediated by the retained farnesyl group. To better characterize the protein-membrane interface, we quantified binding of purified recombinant ∆50LA tail domain (∆50LA-TD) to tethered bilayer membranes composed of phosphatidylserine and phosphocholine using surface plasmon resonance. Farnesylated ∆50LA-TD binds to the membrane interface only in the presence of Ca(2+) or Mg(2+) at physiological ionic strength. At extremely low ionic strength, both the farnesylated and non-farnesylated forms of ∆50LA-TD bind to the membrane surface in amounts that exceed those expected for a densely packed protein monolayer. Interestingly, the wild-type LA-TD with no farnesylation also associates with membranes at low ionic strength but forms only a single layer. We suggest that electrostatic interactions are mediated by charge clusters with a net positive charge that we calculate on the surface of the LA-TDs. These studies suggest that the accumulation of ∆50LA at the inner nuclear membrane observed in cells is due to a combination of aggregation and membrane association rather than simple membrane binding; electrostatics plays an important role in mediating this association.
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kalinowski
authors.affiliation: Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States.
authors.forename: Peter N
authors.initials: PN
authors.lastname: Yaron
authors.affiliation: Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Qin
authors.affiliation: Department of Physics, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Shenoy
authors.affiliation: Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Buehler
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States; Department of Civil and Environmental Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, United States. Electronic address: quench@cmu.edu.
authors.forename: Mathias
authors.initials: M
authors.lastname: Lösche
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, United States. Electronic address: krisdahl@cmu.edu.
authors.forename: Kris Noel
authors.initials: KN
authors.lastname: Dahl
mesh_terms: D002118:Calcium / Q000737:chemistry; D006801:Humans; D007477:Ions / Q000737:chemistry; D034904:Lamin Type A / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D009994:Osmolar Concentration; D010718:Phosphatidylserines / Q000737:chemistry; D010767:Phosphorylcholine / Q000737:chemistry; D011371:Progeria / Q000378:metabolism / Q000473:pathology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance
chemical_list: D007477:Ions; D034904:Lamin Type A; D008051:Lipid Bilayers; D010718:Phosphatidylserines; D010767:Phosphorylcholine; D008274:Magnesium; D002118:Calcium
keywords: Farnesylation; Hutchinson–Gilford progeria syndrome; Lamin A; Protein–membrane