Ca2+ regulates the Drosophila Stoned-A and Stoned-B proteins interaction with the C2B domain of Synaptotagmin-1.
The dicistronic Drosophila stoned gene is involved in exocytosis and/or endocytosis of synaptic vesicles. Mutations in either stonedA or stonedB cause a severe disruption of neurotransmission in fruit flies. Previous studies have shown that the coiled-coil domain of the Stoned-A and the µ-homology domain of the Stoned-B protein can interact with the C2B domain of Synaptotagmin-1. However, very little is known about the mechanism of interaction between the Stoned proteins and the C2B domain of Synaptotagmin-1. Here we report that these interactions are increased in the presence of Ca(2+). The Ca(2+)-dependent interaction between the µ-homology domain of Stoned-B and C2B domain of Synaptotagmin-1 is affected by phospholipids. The C-terminal region of the C2B domain, including the tryptophan-containing motif, and the Ca(2+) binding loop region that modulate the Ca(2+)-dependent oligomerization, regulates the binding of the Stoned-A and Stoned-B proteins to the C2B domain. Stoned-B, but not Stoned-A, interacts with the Ca(2+)-binding loop region of C2B domain. The results indicate that Ca(2+)-induced self-association of the C2B domain regulates the binding of both Stoned-A and Stoned-B proteins to Synaptotagmin-1. The Stoned proteins may regulate sustainable neurotransmission in vivo by binding to Ca(2+)-bound Synaptotagmin-1 associated synaptic vesicles.
Department of Genetics, The University of Melbourne, Parkville, Victoria, Australia. carolina.soekmadji@qut.edu.au
Carolina
C
Soekmadji
Clement
C
Angkawidjaja
Leonard E
LE
Kelly
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004330:Drosophila / Q000378:metabolism* / Q000502:physiology; D029721:Drosophila Proteins / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism*; D050863:Synaptotagmin I / Q000378:metabolism*
D002352:Carrier Proteins; D017931:DNA Primers; D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; D010743:Phospholipids; D011994:Recombinant Proteins; D050863:Synaptotagmin I; C420113:stnA protein, Drosophila; C420114:stnB protein, Drosophila; D002118:Calcium