title: Binding site asymmetry in human transthyretin: insights from a joint neutron and X-ray crystallographic analysis using perdeuterated protein.
abstract: Human transthyretin has an intrinsic tendency to form amyloid fibrils and is heavily implicated in senile systemic amyloidosis. Here, detailed neutron structural studies of perdeuterated transthyretin are described. The analyses, which fully exploit the enhanced visibility of isotopically replaced hydrogen atoms, yield new information on the stability of the protein and the possible mechanisms of amyloid formation. Residue Ser117 may play a pivotal role in that a single water molecule is closely associated with the γ-hydrogen atoms in one of the binding pockets, and could be important in determining which of the two sites is available to the substrate. The hydrogen-bond network at the monomer-monomer interface is more extensive than that at the dimer-dimer interface. Additionally, the edge strands of the primary dimer are seen to be favourable for continuation of the β-sheet and the formation of an extended cross-β structure through sequential dimer couplings. It is argued that the precursor to fibril formation is the dimeric form of the protein.
authors.affiliation: Facility of Natural Sciences, Institute of Science and Technology in Medicine, Keele University , Staffordshire ST5 5BG, United Kingdom ; Institut Laue-Langevin , 71, avenue des Martyrs, Grenoble, CS 20156, France ; Partnership for Structural Biology , 71, avenue des Martyrs, Grenoble, CS 20156, France.
authors.forename: Melina
authors.initials: M
authors.lastname: Haupt
authors.affiliation: Institut Laue-Langevin , 71, avenue des Martyrs, Grenoble, CS 20156, France ; Partnership for Structural Biology , 71, avenue des Martyrs, Grenoble, CS 20156, France.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Blakeley
authors.affiliation: Department of Molecular Biology, University of Salzburg , Billrothstrasse 11, Salzburg, 5020, Austria ; Diamond Light Source , Didcot, Oxfordshire OX11 0DE, United Kingdom.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Fisher
authors.affiliation: Institut Laue-Langevin , 71, avenue des Martyrs, Grenoble, CS 20156, France.
authors.forename: Sax A
authors.initials: SA
authors.lastname: Mason
authors.affiliation: Division of Medicine (Royal Free Campus), University College London , Rowland Hill Street, London NW3 2PF, United Kingdom.
authors.forename: Jon B
authors.initials: JB
authors.lastname: Cooper
authors.affiliation: Business Development Office, European Synchrotron Radiation Facility , Grenoble, 38042, France ; Facility of Natural Sciences, Institute of Science and Technology in Medicine, Keele University , Staffordshire ST5 5BG, United Kingdom ; Partnership for Structural Biology , 71, avenue des Martyrs, Grenoble, CS 20156, France.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Mitchell
authors.affiliation: Facility of Natural Sciences, Institute of Science and Technology in Medicine, Keele University , Staffordshire ST5 5BG, United Kingdom ; Institut Laue-Langevin , 71, avenue des Martyrs, Grenoble, CS 20156, France ; Partnership for Structural Biology , 71, avenue des Martyrs, Grenoble, CS 20156, France.
authors.forename: V Trevor
authors.initials: VT
authors.lastname: Forsyth
keywords: amyloid assembly; deuteration; neutron crystallography; transthyretin