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J Neurosci. 2015 Feb 11;35(6):2492-507. doi: 10.1523/JNEUROSCI.4248-14.2015.

Phosphorylation of synaptic vesicle protein 2A at Thr84 by casein kinase 1 family kinases controls the specific retrieval of synaptotagmin-1.

Author information

1
Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and.
2
Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom.
3
Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, Scotland, United Kingdom m.cousin@ed.ac.uk d.r.alessi@dundee.ac.uk.
4
Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, United Kingdom, and m.cousin@ed.ac.uk d.r.alessi@dundee.ac.uk.

Abstract

Synaptic vesicle protein 2A (SV2A) is a ubiquitous component of synaptic vesicles (SVs). It has roles in both SV trafficking and neurotransmitter release. We demonstrate that Casein kinase 1 family members, including isoforms of Tau-tubulin protein kinases (TTBK1 and TTBK2), phosphorylate human SV2A at two constellations of residues, namely Cluster-1 (Ser42, Ser45, and Ser47) and Cluster-2 (Ser80, Ser81, and Thr84). These residues are also phosphorylated in vivo, and the phosphorylation of Thr84 within Cluster-2 is essential for triggering binding to the C2B domain of human synaptotagmin-1. We show by crystallographic and other analyses that the phosphorylated Thr84 residue binds to a pocket formed by three conserved Lys residues (Lys314, Lys326, and Lys328) on the surface of the synaptotagmin-1 C2B domain. Finally, we observed dysfunctional synaptotagmin-1 retrieval during SV endocytosis by ablating its phospho-dependent interaction with SV2A, knockdown of SV2A, or rescue with a phosphorylation-null Thr84 SV2A mutant in primary cultures of mouse neurons. This study reveals fundamental details of how phosphorylation of Thr84 on SV2A controls its interaction with synaptotagmin-1 and implicates SV2A as a phospho-dependent chaperone required for the specific retrieval of synaptotagmin-1 during SV endocytosis.

KEYWORDS:

CK1; SV2A; synaptotagmin

PMID:
25673844
PMCID:
PMC4323530
DOI:
10.1523/JNEUROSCI.4248-14.2015
[Indexed for MEDLINE]
Free PMC Article

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