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Pierre Montaville

Publications and source records attributed to Pierre Montaville.

5 recordsLinked to original sources
PubMed2006

The C2A-C2B linker defines the high affinity Ca(2+) binding mode of rabphilin-3A.

The Ca(2+) binding properties of C2 domains are essential for the function of their host proteins. We present here the first crystal structures showing an unexpected Ca(2+) 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 Ca(2+)-binding region of the C2B domain. Because of these interactions, the coordination sphere of the two bound Ca(2+) ions is almost complete. Mutation of these acidic residues to alanine resulted in a 10-fold decrease in the intrinsic Ca(2+) binding affinity of the C2B domain. Using NMR spectroscopy, we show that this interaction occurred only in the Ca(2+)-bound state of the C2B domain. In addition, this Ca(2+) 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 Ca(2+) binding mode not only shows how a C2 domain increases its intrinsic Ca(2+) affinity, but also provides the structural base for an atypical protein-Ca(2+)-phospholipid binding mode of rabphilin-3A.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Structure of the C2A domain of rabphilin-3A.

Rabphilin-3A is a neuronal protein containing a C2-domain tandem. To date, only the structure of the C2B domain has been solved. The crystal structure of the Ca2+-free C2A domain has been solved by molecular replacement and refined to 1.92 A resolution. It adopts the classical C2-domain fold consisting of an eight-stranded antiparallel beta-sandwich with type I topology. In agreement with its Ca2+-dependent negatively charged membrane-binding properties, this C2 domain contains all the conserved acidic residues responsible for calcium binding. However, the replacement of a conserved aspartic acid residue by glutamic acid allows formation of an additional strong hydrogen bond, resulting in increased rigidity of calcium-binding loop 1. The electrostatic surface of the C2A domain consists of a large positively charged belt surrounded by two negatively charged patches located at both tips of the domain. In comparison, the structurally very similar C2A domain of synaptotagmin I has a highly acidic electrostatic surface, suggesting completely unrelated functions for these two C2A domains.

Adaptor Proteins, Signal Transducing↗
PubMed2002

A new consensus sequence for phosphatidylserine recognition by annexins.

Annexins are abundant and ubiquitous proteins that bind, by their four structurally identical domain cores, to phosphatidylserine-containing membranes in the presence of Ca2+. Using molecular simulation and mutagenesis, we have identified a new phosphatidylserine-binding site in annexin V domain 1 and established its structure. The residues involved in this site constitute a consensus sequence highly conserved in all annexins. Remarkably, this consensus sequence is exclusively found in domains 1 or 2, sometimes in both, but never in domains 3 and 4. Such a pattern actually delineates three classes of annexins, shedding new light on the role played by the four-domain core of annexins that could encode specific information discriminating the different annexins that compete within a given cell for membrane binding. Our findings thus provide new strategies for understanding the regulation of the cellular functions of annexins.

Amino Acid Sequence↗