title: Functional analysis of the interface between the tandem C2 domains of synaptotagmin-1.
abstract: C2 domains are widespread motifs that often serve as Ca(2+)-binding modules; some proteins have more than one copy. An open issue is whether these domains, when duplicated within the same parent protein, interact with one another to regulate function. In the present study, we address the functional significance of interfacial residues between the tandem C2 domains of synaptotagmin (syt)-1, a Ca(2+) sensor for neuronal exocytosis. Substitution of four residues, YHRD, at the domain interface, disrupted the interaction between the tandem C2 domains, altered the intrinsic affinity of syt-1 for Ca(2+), and shifted the Ca(2+) dependency for binding to membranes and driving membrane fusion in vitro. When expressed in syt-1 knockout neurons, the YHRD mutant yielded reductions in synaptic transmission, as compared with the wild-type protein. These results indicate that physical interactions between the tandem C2 domains of syt-1 contribute to excitation-secretion coupling.
authors.affiliation: Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53705-2275 Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705-2275 Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, Madison, WI 53705-2275.
authors.forename: Chantell S
authors.initials: CS
authors.lastname: Evans
authors.affiliation: Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53705-2275 Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705-2275.
authors.forename: Zixuan
authors.initials: Z
authors.lastname: He
authors.affiliation: Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53705-2275 Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705-2275.
authors.forename: Hua
authors.initials: H
authors.lastname: Bai
authors.affiliation: Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53705-2275 Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705-2275.
authors.forename: Xiaochu
authors.initials: X
authors.lastname: Lou
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK.
authors.forename: Pia
authors.initials: P
authors.lastname: Jeggle
authors.affiliation: Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX 79430.
authors.forename: R Bryan
authors.initials: RB
authors.lastname: Sutton
authors.affiliation: Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Edwardson
authors.affiliation: Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53705-2275 Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705-2275 Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, Madison, WI 53705-2275 chapman@wisc.edu.
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Chapman
mesh_terms: D000818:Animals; D000070538:C2 Domains; D002118:Calcium / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D009435:Synaptic Transmission; D050863:Synaptotagmin I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D050863:Synaptotagmin I; C494312:Syt1 protein, rat; D002118:Calcium