Structural and mutational analysis of functional differentiation between synaptotagmins-1 and -7

Mingshan Xue, Timothy K. Craig, Ok Ho Shin, Liyi Li, Chad A Brautigam, Diana R Tomchick, Thomas C. Südhof, Christian Rosenmund, Jose Rizo-Rey

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Synaptotagmins are known to mediate diverse forms of Ca2+-triggered exocytosis through their C2 domains, but the principles underlying functional differentiation among them are unclear. Synaptotagmin-1 functions as a Ca2+ sensor in neurotransmitter release at central nervous system synapses, but synaptotagmin-7 does not, and yet both isoforms act as Ca2+ sensors in chromaffin cells. To shed light into this apparent paradox, we have performed rescue experiments in neurons from synaptotagmin-1 knockout mice using a chimera that contains the synaptotagmin-1 sequence with its C2B domain replaced by the synaptotagmin-7 C2B domain (Syt1/7). Rescue was not achieved either with the WT Syt1/7 chimera or with nine mutants where residues that are distinct in synaptotagmin-7 were restored to those present in synaptotagmin-1. To investigate whether these results arise because of unique conformational features of the synaptotagmin-7 C2B domain, we determined its crystal structure at 1.44 Å resolution. The synaptotagmin-7 C2B domain structure is very similar to that of the synaptotagmin-1 C2B domain and contains three Ca2+-binding sites. Two of the Ca2+-binding sites of the synaptotagmin-7 C2B domain are also present in the synaptotagmin-1 C2B domain and have analogous ligands to those determined for the latter by NMR spectroscopy, suggesting that a discrepancy observed in a crystal structure of the synaptotagmin-1 C2B domain arose from crystal contacts. Overall, our results suggest that functional differentiation in synaptotagmins arises in part from subtle sequence changes that yield dramatic functional differences.

Original languageEnglish (US)
Article numbere12544
Pages (from-to)1-12
Number of pages12
JournalPLoS One
Volume5
Issue number9
DOIs
StatePublished - 2010

Fingerprint

Synaptotagmin I
Synaptotagmins
calcium
chimerism
crystal structure
binding sites
chromaffin cells
exocytosis
synapse
neurotransmitters
Crystal structure
Binding Sites
central nervous system
crystals
nuclear magnetic resonance spectroscopy
Chromaffin Cells
neurons
Sensors
Exocytosis
Neurology

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Structural and mutational analysis of functional differentiation between synaptotagmins-1 and -7. / Xue, Mingshan; Craig, Timothy K.; Shin, Ok Ho; Li, Liyi; Brautigam, Chad A; Tomchick, Diana R; Südhof, Thomas C.; Rosenmund, Christian; Rizo-Rey, Jose.

In: PLoS One, Vol. 5, No. 9, e12544, 2010, p. 1-12.

Research output: Contribution to journalArticle

Xue, Mingshan ; Craig, Timothy K. ; Shin, Ok Ho ; Li, Liyi ; Brautigam, Chad A ; Tomchick, Diana R ; Südhof, Thomas C. ; Rosenmund, Christian ; Rizo-Rey, Jose. / Structural and mutational analysis of functional differentiation between synaptotagmins-1 and -7. In: PLoS One. 2010 ; Vol. 5, No. 9. pp. 1-12.
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