title: Biophysical assay for tethered signaling reactions reveals tether-controlled activity for the phosphatase SHP-1.
abstract: Tethered enzymatic reactions are ubiquitous in signaling networks but are poorly understood. A previously unreported mathematical analysis is established for tethered signaling reactions in surface plasmon resonance (SPR). Applying the method to the phosphatase SHP-1 interacting with a phosphorylated tether corresponding to an immune receptor cytoplasmic tail provides five biophysical/biochemical constants from a single SPR experiment: two binding rates, two catalytic rates, and a reach parameter. Tether binding increases the activity of SHP-1 by 900-fold through a binding-induced allosteric activation (20-fold) and a more significant increase in local substrate concentration (45-fold). The reach parameter indicates that this local substrate concentration is exquisitely sensitive to receptor clustering. We further show that truncation of the tether leads not only to a lower reach but also to lower binding and catalysis. This work establishes a new framework for studying tethered signaling processes and highlights the tether as a control parameter in clustered receptor signaling.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, U.K.
authors.forename: Jesse
authors.identifier: 0000-0002-1008-1890
authors.initials: J
authors.lastname: Goyette
authors.affiliation: Wolfson Centre for Mathematical Biology, University of Oxford, Oxford, U.K.
authors.forename: Citlali Solis
authors.identifier: 0000-0002-1475-1206
authors.initials: CS
authors.lastname: Salas
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, U.K.
authors.forename: Nicola
authors.initials: N
authors.lastname: Coker-Gordon
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, U.K.
authors.forename: Marcus
authors.initials: M
authors.lastname: Bridge
authors.affiliation: Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA.
authors.forename: Samuel A
authors.identifier: 0000-0002-7543-8619
authors.initials: SA
authors.lastname: Isaacson
authors.affiliation: Department of Mathematics, University of California, Irvine, Irvine, CA 92697, USA.
authors.forename: Jun
authors.identifier: 0000-0002-2758-4515
authors.initials: J
authors.lastname: Allard
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, U.K.; Wolfson Centre for Mathematical Biology, University of Oxford, Oxford, U.K.
authors.forename: Omer
authors.identifier: 0000-0001-5847-5226
authors.initials: O
authors.lastname: Dushek
mesh_terms: D002384:Catalysis; D006801:Humans; D008958:Models, Molecular; D000072417:Protein Domains; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6
keywords: Biochemistry; SHP-1; allosteric activation; clustered receptors; enzymatic catalysis; mathematical model; stochastic simulations; surface plasmon resonance; tethered signalling; tyrosine phosphatase