The C2A-C2B linker defines the high affinity Ca2+ binding mode of rabphilin-3A
2007 | journal article. A publication with affiliation to the University of Göttingen.
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The C2A-C2B linker defines the high affinity Ca2+ binding mode of rabphilin-3A
Montaville, P.; Schlicker, C.; Leonov, A.; Zweckstetter, M.; Sheldrick, G. M. & Becker, S. (2007)
Journal of Biological Chemistry, 282(7) pp. 5015-5025. DOI: https://doi.org/10.1074/jbc.M606746200
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- Authors
- Montaville, Pierre; Schlicker, Christine; Leonov, Andrei; Zweckstetter, Markus; Sheldrick, George M.; Becker, Stefan
- Abstract
- The Ca2+ binding properties of C2 domains are essential for the function of their host proteins. We present here the first crystal structures showing an unexpected Ca2+ binding mode of the C2B domain of rabphilin-3A in atomic detail. Acidic residues from the linker region between the C2A and C2B domains of rabphilin-3A interact with the Ca2+-binding region of the C2B domain. Because of these interactions, the coordination sphere of the two bound Ca2+ ions is almost complete. Mutation of these acidic residues to alanine resulted in a 10-fold decrease in the intrinsic Ca2+ binding affinity of the C2B domain. Using NMR spectroscopy, we show that this interaction occurred only in the Ca2+-bound state of the C2B domain. In addition, this Ca2+ binding mode was maintained in the C2 domain tandem fragment. In NMR-based liposome binding assays, the linker was not released upon phospholipid binding. Therefore, this unprecedented Ca2+ binding mode not only shows how a C2 domain increases its intrinsic Ca2+ affinity, but also provides the structural base for an atypical protein-Ca2+-phospholipid binding mode of rabphilin-3A.
- Issue Date
- 2007
- Status
- published
- Publisher
- Amer Soc Biochemistry Molecular Biology Inc
- Journal
- Journal of Biological Chemistry
- ISSN
- 0021-9258