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Ferjani I, Fattoum A, Maciver S, Bénistant C, Chahinian A, Manai M, Benyamin Y, Roustan C. A direct interaction with calponin inhibits the actin-nucleating activity of gelsolin. Biochem J 2006; 396:461-8. [PMID: 16536729 PMCID: PMC1482823 DOI: 10.1042/bj20051690] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 03/02/2006] [Accepted: 03/15/2006] [Indexed: 12/26/2022]
Abstract
Gelsolin and calponin are well-characterized cytoskeletal proteins that are abundant and widely expressed in vertebrate tissues. It is also becoming apparent, however, that they are involved in cell signalling. In the present study, we show that gelsolin and calponin interact directly to form a high-affinity (K(d)=16 nM) 1:1 complex, by the use of fluorescent probes attached to both proteins, by affinity chromatography and by immunoprecipitation. These methods show that gelsolin can form high-affinity complexes with two calponin isoforms (basic h1 and acidic h3). They also show that gelsolin binds calponin through regions that have been identified previously as being calponin's actin-binding sites. Moreover, gelsolin does not interact with calponin while calponin is bound to F-actin. Reciprocal experiments to find calponin-binding sites on gelsolin show that these are in both the N- and C-terminal halves of gelsolin. Calponin has minimal effects on actin severing by gelsolin. In contrast, calponin markedly affects the nucleation activity of gelsolin. The maximum inhibition of nucleation by gelsolin was 50%, which was achieved with a ratio of two calponins for every gelsolin. Thus the interaction of calponin with gelsolin may play a regulatory role in the formation of actin filaments through modulation of gelsolin's actin-binding function and through the prevention of calponin's actin-binding activities.
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Affiliation(s)
- Imen Ferjani
- *UMR 5539 (CNRS) Laboratoire de Motilité Cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
- †Unité de Biochimie et Biololgie Moléculaire, Faculté des Sciences de Tunis, Campus Universitaire 2092 El Manar, Tunis, Tunisia
| | - Abdellatif Fattoum
- ‡School of Biomedical and Clinical Laboratory Sciences, Division of Biomedical Sciences, College of Medicine, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland
| | - Sutherland K. Maciver
- §Centre de Recherches de Biochimie Macromoléculaire, FRE 2593 (CNRS), 1919 rte de Mende, 34293 Montpellier Cedex 5, France
| | - Christine Bénistant
- ‡School of Biomedical and Clinical Laboratory Sciences, Division of Biomedical Sciences, College of Medicine, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland
| | - Anne Chahinian
- *UMR 5539 (CNRS) Laboratoire de Motilité Cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Mohamed Manai
- †Unité de Biochimie et Biololgie Moléculaire, Faculté des Sciences de Tunis, Campus Universitaire 2092 El Manar, Tunis, Tunisia
| | - Yves Benyamin
- *UMR 5539 (CNRS) Laboratoire de Motilité Cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Claude Roustan
- *UMR 5539 (CNRS) Laboratoire de Motilité Cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
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Méré J, Chahinian A, Maciver S, Fattoum A, Bettache N, Benyamin Y, Roustan C. Gelsolin binds to polyphosphoinositide-free lipid vesicles and simultaneously to actin microfilaments. Biochem J 2005; 386:47-56. [PMID: 15527423 PMCID: PMC1134765 DOI: 10.1042/bj20041054] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gelsolin is a calcium-, pH- and lipid-dependent actin filament severing/capping protein whose main function is to regulate the assembly state of the actin cytoskeleton. Gelsolin is associated with membranes in cells, and it is generally assumed that this interaction is mediated by PPIs (polyphosphoinositides), since an interaction with these lipids has been characterized in vitro. We demonstrate that non-PPI lipids also bind gelsolin, especially at low pH. The data suggest further that gelsolin becomes partially buried in the lipid bilayer under mildly acidic conditions, in a manner that is not dependent of the presence of PPIs. Our data also suggest that lipid binding involves a number of sites that are spread throughout the gelsolin molecule. Linker regions between gelsolin domains have been implicated by other work, notably the linker between G1 and G2 (gelsolin domains 1 and 2 respectively), and we postulate that the linker region between the N-terminal and C-terminal halves of gelsolin (between G3 and G4) is also involved in the interaction with lipids. This region is compatible with other studies in which additional binding sites have been located within G4-6. The lipid-gelsolin interactions reported in the present paper are not calcium-dependent, and are likely to involve significant conformational changes to the gelsolin molecule, as the chymotryptic digest pattern is altered by the presence of lipids under our conditions. We also report that vesicle-bound gelsolin is capable of binding to actin filaments, presumably through barbed end capping. Gelsolin bound to vesicles can nucleate actin assembly, but is less active in severing microfilaments.
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Affiliation(s)
- Jocelyn Méré
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Anne Chahinian
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Sutherland K. Maciver
- †School of Biomedical and Clinical Laboratory Sciences, Division of Biomedical Sciences, College of Medicine, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh EH8 9XD, Scotland, U.K
| | - Abdellatif Fattoum
- ‡Centre de Recherches de Biochimie Macromoléculaire, FRE 2593 (CNRS), 1919 rte de Mende, 34293 Montpellier Cedex 5, France
| | - Nadir Bettache
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Yves Benyamin
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
| | - Claude Roustan
- *UMR 5539 (CNRS) Laboratoire de motilité cellulaire (Ecole Pratique des Hautes Etudes), Université de Montpellier 2, Place E. Bataillon, CC107, 34095 Montpellier Cedex 5, France
- To whom correspondence should be addressed (email )
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