Structural Basis for the Association of MAP6 Protein with Microtubules and Its Regulation by Calmodulin.: Microtubule and calmodulin binding on Mn modules of MAP6

Julien Lefèvre 1, * Philippe Savarin 1 Pierre Gans 2 Loïc Hamon 1 Marie-Jeanne Clément 1 Marie-Odile David 1 Christophe Bosc 3 Annie Andrieux 4 Patrick Curmi 1
* Auteur correspondant
2 LRMN - Laboratoire de Résonance Magnétique Nucléaire
IBS - UMR 5075 - Institut de biologie structurale
3 INSERM U836, équipe 1, Physiopathologie du cytosquelette
GIN - Grenoble Institut des Neurosciences
4 INSERM U836, équipe 1, Physiopathologie du cytosquelette
GPC-GIN - Groupe Physiopathologie du Cytosquelette, GIN - Grenoble Institut des Neurosciences
Abstract : Microtubules are highly dynamic αβ-tubulin polymers. In vitro and in living cells, microtubules are most often cold- and nocodazole-sensitive. When present, the MAP6/STOP family of proteins protects microtubules from cold- and nocodazole-induced depolymerization but the molecular and structure determinants by which these proteins stabilize microtubules remain under debate. We show here that a short protein fragment from MAP6-N, which encompasses its Mn1 and Mn2 modules (MAP6(90-177)), recapitulates the function of the full-length MAP6-N protein toward microtubules, i.e. its ability to stabilize microtubules in vitro and in cultured cells in ice-cold conditions or in the presence of nocodazole. We further show for the first time, using biochemical assays and NMR spectroscopy, that these effects result from the binding of MAP6(90-177) to microtubules with a 1:1 MAP6(90-177):tubulin heterodimer stoichiometry. NMR data demonstrate that the binding of MAP6(90-177) to microtubules involve its two Mn modules but that a single one is also able to interact with microtubules in a closely similar manner. This suggests that the Mn modules represent each a full microtubule binding domain and that MAP6 proteins may stabilize microtubules by bridging tubulin heterodimers from adjacent protofilaments or within a protofilament. Finally, we demonstrate that Ca(2+)-calmodulin competes with microtubules for MAP6(90-177) binding and that the binding mode of MAP6(90-177) to microtubules and Ca(2+)-calmodulin involves a common stretch of amino acid residues on the MAP6(90-177) side. This result accounts for the regulation of microtubule stability in cold condition by Ca(2+)-calmodulin.
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Article dans une revue
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2013, 288 (34), pp.24910-22. 〈10.1074/jbc.M113.457267〉
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Soumis le : lundi 7 juillet 2014 - 15:50:23
Dernière modification le : lundi 19 février 2018 - 14:34:04
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Julien Lefèvre, Philippe Savarin, Pierre Gans, Loïc Hamon, Marie-Jeanne Clément, et al.. Structural Basis for the Association of MAP6 Protein with Microtubules and Its Regulation by Calmodulin.: Microtubule and calmodulin binding on Mn modules of MAP6. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2013, 288 (34), pp.24910-22. 〈10.1074/jbc.M113.457267〉. 〈inserm-00858655〉

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