Patrick Chaussepied

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In previous work, we studied the early steps of the Mg(2+)-ATPase activity of Ca(2+)-activated myofibrils [Houadjeto, M., Travers, F., & Barman, T. (1992) Biochemistry 31, 1564-1569]. The myofibrils were free to contract, and the results obtained refer to the ATPase cycle of myofibrils contracting with no external load. Here we studied the ATPase of(More)
HsEg5 is a human kinesin-related motor protein essential for the formation of a bipolar mitotic spindle. It interacts with the mitotic centrosomes in a phosphorylation-dependent manner. To investigate further the mechanisms involved in targetting HsEg5 to the spindle apparatus, we expressed various mutants of HsEg5 in HeLa cells. All these mutants share a(More)
The properties of polymerization and interaction of the G-actin-myosin S1 complexes (formed with either the S1(A1) or the S1(A2) isoform) have been studied by light-scattering and fluorescence measurements in the absence and in the presence of DNase I. In the absence of DNase I, the G-actin-S1(A1) and G-actin-S1(A2) complexes were found to be characterized(More)
The functional and structural properties of the monomeric and filamentous actin-myosin head (S1) complexes were compared under strictly controlled conditions which avoid the S1-induced polymerization of monomeric actin. Under these conditions, monomeric (G) and filamentous (F) actin were found to activate S1 Mg(2+)-ATPase by 3- and 120-fold, respectively,(More)
We have characterized various structural and enzymatic properties of the (68K-30K)-S-1 derivative obtained by thrombic cleavage [Chaussepied, P., Mornet, D., Audemard, E., Derancourt, J., & Kassab, R. (1986) Biochemistry (preceding paper in this issue)]. The far-ultraviolet CD spectra and thiol reactivity measurements indicated an unchanged overall(More)
F-actin specifically substituted with the photocross-linker, p-azidophenylglyoxal, at Arg95 and Arg28 was isolated and characterized. Upon complexation with myosin subfragment-1 (S1) and photolysis at 365 nm, it was readily cross-linked to the S1 heavy chain with a yield of about 13-25%, generating four major actin-heavy-chain adducts with molecular masses(More)
The interaction between skeletal myosin subfragment 1 (S1) and filamentous actin was examined at various intermediate states of the actomyosin ATPase cycle by chemical cross-linking experiments. Reaction of the actin-S1 complex with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide and N-hydroxysuccinimide generated products with molecular masses of 165 and(More)
Myosin subfragment-1 (S1) can be cross-linked to two actin monomers by 1-ethyl-3-[3-(dimethylamino)-propyl]-carbodiimide only when F-actin is in excess over S1. Electron micrographs of the covalent actin2-S1 complex showed that S1 was cross-linked to two adjacent monomers of the same actin filament. Cross-linking experiments with pre-proteolyzed S1(More)
The two main proteins involved in muscular contraction and cell motility, myosin and actin, possess the intrinsic property of being able to form filamentous structures. This property poses a serious impediment to the study of their structures and interactions, and a considerable effort has thus been made to isolate their functional domains. The globular(More)
We have designed an "antipeptide" capable of firmly and specifically interacting with a preselected stretch of myosin S-1 heavy chain. Covalent attachment of this antipeptide to its target stretch, residues 633-642, does not affect the intrinsic ATPase activities of the protein but significantly reduces the actin-binding capabilities of the myosin head.