Abstract
At nerve terminals, a focal and transient increase in intracellular Ca2+ triggers the fusion of neurotransmitter-filled vesicles with the plasma membrane. The most extensively studied candidate for the Ca2+-sensing trigger is synaptotagmin I, whose Ca2+-dependent interactions with acidic phospholipids and syntaxin1 have largely been ascribed to its C2A domain2,3,4,5,6, although the C2B domain also binds Ca2+ (refs 7, 8). Genetic tests of synaptotagmin I have been equivocal as to whether it is the Ca2+-sensing trigger of fusion6,9,10,11,12,13,14,15. Synaptotagmin IV, a related isoform that does not bind Ca2+ in the C2A domain, might be an inhibitor of release16,17. We mutated an essential aspartate of the Ca2+-binding site of the synaptotagmin I C2A domain and expressed it in Drosophila lacking synaptotagmin I. Here we show that, despite the disruption of the binding site, the Ca2+-dependent properties of transmission were not altered. Similarly, we found that synaptotagmin IV could substitute for synaptotagmin I. We conclude that the C2A domain of synaptotagmin is not required for Ca2+-dependent synaptic transmission, and that synaptotagmin IV promotes rather than inhibits transmission.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
Purchase on Springer Link
Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Chapman, E. R., Hanson, P. I., An, S. & Jahn, R. Ca2+ regulates the interaction between synaptotagmin and syntaxin 1. J. Biol. Chem. 270, 23667–23671 (1995)
Chapman, E. R. & Jahn, R. Calcium-dependent interaction of the cytoplasmic region of synaptotagmin with membranes. Autonomous function of a single C2-homologous domain. J. Biol. Chem. 269, 5735–5741 (1994)
Davletov, B. A. & Sudhof, T. C. A single C2 domain from synaptotagmin I is sufficient for high affinity Ca2+/phospholipid binding. J. Biol. Chem. 268, 26386–26390 (1993)
Kee, Y. & Scheller, R. H. Localization of synaptotagmin-binding domains on syntaxin. J. Neurosci. 16, 1975–1981 (1996)
Li, C., Davletov, B. A. & Sudhof, T. C. Distinct Ca2+ and Sr2 + binding properties of synaptotagmins. Definition of candidate Ca2+ sensors for the fast and slow components of neurotransmitter release. J. Biol. Chem. 270, 24898–24902 (1995)
Fernandez-Chacon, R. et al. Synaptotagmin I functions as a calcium regulator of release probability. Nature 410, 41–49 (2001)
Damer, C. K. & Creutz, C. E. Synergistic membrane interactions of the two C2 domains of synaptotagmin. J. Biol. Chem. 269, 31115–31123 (1994)
Desai, R. C. et al. The C2B domain of synaptotagmin is a Ca2+-sensing module essential for exocytosis. J. Cell Biol. 150, 1125–1136 (2000)
Nonet, M. L., Grundahl, K., Meyer, B. J. & Rand, J. B. Synaptic function is impaired but not eliminated in C. elegans mutants lacking synaptotagmin. Cell 73, 1291–1305 (1993)
Broadie, K., Bellen, H. J., DiAntonio, A., Littleton, J. T. & Schwarz, T. L. Absence of synaptotagmin disrupts excitation-secretion coupling during synaptic transmission. Proc. Natl Acad. Sci. USA 91, 10727–10731 (1994)
DiAntonio, A. & Schwarz, T. L. The effect on synaptic physiology of synaptotagmin mutations in Drosophila. Neuron 12, 909–920 (1994)
Littleton, J. T., Stern, M., Perin, M. & Bellen, H. J. Calcium dependence of neurotransmitter release and rate of spontaneous vesicle fusions are altered in Drosophila synaptotagmin mutants. Proc. Natl Acad. Sci. USA 91, 10888–10892 (1994)
Geppert, M. et al. Synaptotagmin I: a major Ca2+ sensor for transmitter release at a central synapse. Cell 79, 717–727 (1994)
Jorgensen, E. M. et al. Defective recycling of synaptic vesicles in synaptotagmin mutants of Caenorhabditis elegans. Nature 378, 196–199 (1995)
Reist, N. E. et al. Morphologically docked synaptic vesicles are reduced in synaptotagmin mutants of Drosophila. J. Neurosci. 18, 7662–7673 (1998)
Littleton, J. T., Serano, T. L., Rubin, G. M., Ganetzky, B. & Chapman, E. R. Synaptic function modulated by changes in the ratio of synaptotagmin I and IV. Nature 400, 757–760 (1999)
Wang, C. T. et al. Synaptotagmin modulation of fusion pore kinetics in regulated exocytosis of dense-core vesicles. Science 294, 1111–1115 (2001)
Ubach, J., Zhang, X., Shao, X., Sudhof, T. C. & Rizo, J. Ca2+ binding to synaptotagmin: how many Ca2+ ions bind to the tip of a C2-domain? EMBO J. 17, 3921–3930 (1998)
Li, C. et al. Ca2+-dependent and -independent activities of neural and non-neural synaptotagmins. Nature 375, 594–599 (1995)
Zhang, X., Rizo, J. & Sudhof, T. C. Mechanism of phospholipid binding by the C2A-domain of synaptotagmin I. Biochemistry 37, 12395–12403 (1998)
von Poser, C., Ichtchenko, K., Shao, X., Rizo, J. & Sudhof, T. C. The evolutionary pressure to inactivate. A subclass of synaptotagmins with an amino acid substitution that abolishes Ca2+ binding. J. Biol. Chem. 272, 14314–14319 (1997)
Loewen, C. A., Mackler, J. M. & Reist, N. E. Drosophila synaptotagmin I null mutants survive to early adulthood. Genesis 31, 30–36 (2001)
Rizo, J. & Sudhof, T. C. C2-domains, structure and function of a universal Ca2+-binding domain. J. Biol. Chem. 273, 15879–15882 (1998)
Mackler, J. M., Drummond, J. A., Loewen, C. A., Robinson, I. M. & Reist, N. E. The C2B Ca2+-binding motif of synaptotagmin is required for synaptic transmission in vivo. Nature advance online publication, 7 July 2002 (doi:10.1038/nature00846)
Neher, E. & Penner, R. Mice sans synaptotagmin. Nature 372, 316–317 (1994)
Voets, T. et al. Intracellular calcium dependence of large dense-core vesicle exocytosis in the absence of synaptotagmin I. Proc. Natl Acad. Sci. USA 98, 11680–11685 (2001)
Zhang, J. Z., Davletov, B. A., Sudhof, T. C. & Anderson, R. G. Synaptotagmin I is a high affinity receptor for clathrin AP-2: implications for membrane recycling. Cell 78, 751–760 (1994)
Haucke, V. & De Camilli, P. AP-2 recruitment to synaptotagmin stimulated by tyrosine-based endocytic motifs. Science 285, 1268–1271 (1999)
Burgoyne, R. D. & Morgan, A. Calcium sensors in regulated exocytosis. Cell Calcium 24, 367–376 (1998)
DiAntonio, A., Parfitt, K. O. & Schwartz, T. L. Synaptic transmission persists in synaptotagmin mutants of Drosophila. Cell 73, 1281–1290 (1993)
Martin, A. R. A further study of the statistical composition of the endplate. J. Physiol. 130, 114–122 (1955)
Acknowledgements
We thank I. Inman for technical assistance; N. Reist, J. Li Bryan Stewart and B. Niemeyer for reagents and discussions; and N. Gay and the Department of Biochemistry (Cambridge) for resources. I.M.R. was supported by the American Heart Association, Western Affiliate, and is a Medical Research Council Career Development Award Fellow. The work was supported by the Muscular Dystrophy Association, by a Silvio Conti Center for Neuroscience Award from the National Institute of Mental Health, and by the National Institutes of Health (T.L.S.).
Author information
Authors and Affiliations
Corresponding authors
Ethics declarations
Competing interests
The authors declare that they have no competing financial interests.
Supplementary information
Rights and permissions
About this article
Cite this article
Robinson, I., Ranjan, R. & Schwarz, T. Synaptotagmins I and IV promote transmitter release independently of Ca2+ binding in the C2A domain. Nature 418, 336–340 (2002). https://doi.org/10.1038/nature00915
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/nature00915
This article is cited by
-
Function of Drosophila Synaptotagmins in membrane trafficking at synapses
Cellular and Molecular Life Sciences (2021)
-
Regulation of forward and backward locomotion through intersegmental feedback circuits in Drosophila larvae
Nature Communications (2019)
-
Structural basis for the clamping and Ca2+ activation of SNARE-mediated fusion by synaptotagmin
Nature Communications (2019)
-
Injured astrocytes are repaired by Synaptotagmin XI-regulated lysosome exocytosis
Cell Death & Differentiation (2016)
-
Current techniques for high-resolution mapping of behavioral circuits in Drosophila
Journal of Comparative Physiology A (2015)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.