Synaptic ribbons are needed for fast and continuous exocytosis in ribbon synapses. RIBEYE is a main protein component of synaptic ribbons and is necessary to build the synaptic ribbon. RIBEYE consists of a unique A-domain and a carboxyterminal B-domain, which binds NAD(H). Within the presynaptic terminal, the synaptic ribbons are in physical contact with large numbers of synaptic vesicle (SV)s. How this physical contact between ribbons and synaptic vesicles is established at a molecular level is not well understood. In the present study, we demonstrate that the RIBEYE(B)-domain can directly interact with lipid components of SVs using two different sedimentation assays with liposomes of defined chemical composition. Similar binding results were obtained with a SV-containing membrane fraction. The binding of liposomes to RIBEYE(B) depends upon the presence of a small amount of lysophospholipids present in the liposomes. Interestingly, binding of liposomes to RIBEYE(B) depends on NAD(H) in a redox-sensitive manner. The binding is enhanced by NADH, the reduced form, and is inhibited by NAD+, the oxidized form. Lipid-mediated attachment of vesicles is probably part of a multi-step process that also involves additional, protein-dependent processes.
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Cover Image
Cover Image
Structure of O-acetylserine sulfhydrylase (OASS) from Brucella abortus compared with all known OASS structures. The high degree of variation is observed in N-terminal domain, which determined the size of active site cleft and responsible for interactions with Serine acetyl Transferase. The co-factor Pyridoxal phosphate (PLP) is shown in ball & stick model in the active site. For more information, please see study by Dharavath et al. in this issue, pages 1221–1239. Image provided by Samudrala Gourinath.
RIBEYE(B)-domain binds to lipid components of synaptic vesicles in an NAD(H)-dependent, redox-sensitive manner
Karin Schwarz, Frank Schmitz; RIBEYE(B)-domain binds to lipid components of synaptic vesicles in an NAD(H)-dependent, redox-sensitive manner. Biochem J 1 April 2017; 474 (7): 1205–1220. doi: https://doi.org/10.1042/BCJ20160886
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