PDBsum entry 2k3h

Protein transport

PDB id: 2k3h

Contents

Protein chain

127 a.a. *

Metals

_CA ×2

* Residue conservation analysis

PDB id:

2k3h

Name:

Protein transport

Title:

Structural determinants for ca2+ and pip2 binding by the c2a domain of rabphilin-3a

Structure:

Rabphilin-3a. Chain: a. Fragment: c2a domain (unp residues 368-570). Synonym: c2 domain. Engineered: yes

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Gene: rph3a. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

20 models

Authors:

N.Coudevylle,P.Montaville,A.Leonov,M.Zweckstetter,S.Becker

Key ref:

N.Coudevylle et al. (2008). Structural Determinants for Ca2+ and Phosphatidylinositol 4,5-Bisphosphate Binding by the C2A Domain of Rabphilin-3A. J Biol Chem, 283, 35918-35928. PubMed id: 18945677 DOI: 10.1074/jbc.M804094200

Date:

08-May-08 Release date: 21-Oct-08

Protein chain

P47708  (RP3A_MOUSE) -  Rabphilin-3A from Mus musculus

Seq: 681 a.a.

Struc: 127 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1074/jbc.M804094200

J Biol Chem 283:35918-35928 (2008)

PubMed id: 18945677

Structural Determinants for Ca2+ and Phosphatidylinositol 4,5-Bisphosphate Binding by the C2A Domain of Rabphilin-3A.

N.Coudevylle, P.Montaville, A.Leonov, M.Zweckstetter, S.Becker.

ABSTRACT

Rabphilin-3A is a neuronal C2 domain tandem containing protein involved in vesicle trafficking. Both its C2 domains (C2A and C2B) are able to bind phosphatidylinositol 4,5-bisphosphate, a key player in the neurotransmitter release process. The rabphilin-3A C2A domain has previously been shown to bind inositol-1,4,5-trisphosphate (IP3; phosphatidylinositol 4,5-bisphosphate headgroup) in a Ca(2+)-dependent manner with a relatively high affinity (50 mum) in the presence of saturating concentrations of Ca(2+). Moreover, IP3 and Ca(2+) binding to the C2A domain mutually enhance each other. Here we present the Ca(2+)-bound solution structure of the C2A domain. Structural comparison with the previously published Ca(2+)-free crystal structure revealed that Ca(2+) binding induces a conformational change of Ca(2+) binding loop 3 (CBL3). Our IP3 binding studies as well as our IP3-C2A docking model show the active involvement of CBL3 in IP3 binding, suggesting that the conformational change on CBL3 upon Ca(2+) binding enables the interaction with IP3 and vice versa, in line with a target-activated messenger affinity mechanism. Our data provide detailed structural insight into the functional properties of the rabphilin-3A C2A domain and reveal for the first time the structural determinants of a target-activated messenger affinity mechanism.

Selected figure(s)

Figure 2.
Overall solution structure of the Ca^2^+-bound rabphilin-3A C2A domain. A, backbone superimposition of the final set of 20 structures for the C2A domain. B, representative ribbon model of the C2A domain. Ca^2+ ions are depicted as blue spheres.

Figure 4.
Structure comparison of the Ca^2^+-bound form and Ca^2^+-free form of the rabphilin-3A C2A domain. A, backbone superposition of the Ca^2+-bound solution structure of the C2A domain (in blue) with the Ca^2+-free crystal structure (in gray). B, Ca^2+ binding site comparison of the Ca^2+-bound form (in blue) with the Ca^2+-free form (in gray). Backbones are represented by ribbons, side chains of residues involved in Ca^2+ binding are represented by sticks, and Ca^2+ ions are depicted as blue spheres. C, comparison of the CBL3 conformation in the Ca^2+-bound (blue) and Ca^2+-free (gray) form of the C2A domain.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 35918-35928) copyright 2008.

Figures were selected by an automated process.