Polymerization, three-dimensional structure and mechanical properties of Ddictyostelium versus rabbit muscle actin filaments

Steinmetz, M. O. and Hoenger, A. and Stoffler, D. and Noegel, A. A. and Aebi, U. and Schoenenberger, C. A.. (2000) Polymerization, three-dimensional structure and mechanical properties of Ddictyostelium versus rabbit muscle actin filaments. Journal of molecular biology, Vol. 303, H. 2. pp. 171-184.

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Official URL: http://edoc.unibas.ch/dok/A5258880

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To assess more systematically functional differences among non-muscle and muscle actins and the effect of specific mutations on their function, we compared actin from Dictyostelium discoideum (D-actin) with actin from rabbit skeletal muscle (R-actin) with respect to the formation of filaments, their three-dimensional structure and mechanical properties. With Mg(2+) occupying the single high-affinity divalent cation-binding site, the course of polymerization is very similar for the two types of actin. In contrast, when Ca(2+ )is bound, D-actin exhibits a significantly longer lag phase at the onset of polymerization than R-actin. Crossover spacing and helical screw angle of negatively stained filaments are similar for D and R-F-actin filaments, irrespective of the tightly bound divalent cation. However, three-dimensional helical reconstructions reveal that the intersubunit contacts along the two long-pitch helical strands of D-(Ca)F-actin filaments are more tenuous compared to those in R-(Ca)F-actin filaments. D-(Mg)F-actin filaments on the other hand exhibit more massive contacts between the two long-pitch helical strands than R-(Mg)F-actin filaments. Moreover, in contrast to the structure of R-F-actin filaments which is not significantly modulated by the divalent cation, the intersubunit contacts both along and between the two long-pitch helical strands are weaker in D-(Ca)F-actin compared to D-(Mg)F-actin filaments. Consistent with these structural differences, D-(Ca)F-actin filaments were significantly more flexible than D-(Mg)F-actin.Taken together, this work documents that despite being highly conserved, muscle and non-muscle actins exhibit subtle differences in terms of their polymerization behavior, and the three-dimensional structure and mechanical properties of their F-actin filaments which, in turn, may account for their functional diversity.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Schoenenberger)
UniBasel Contributors:Schoenenberger, Cora-Ann
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:04 Jan 2013 08:35
Deposited On:22 Mar 2012 13:21

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