Türmer K, Orbán J, Gróf P, Nyitrai M. FASCIN and alpha-actinin can regulate the conformation of actin filaments.
Biochim Biophys Acta Gen Subj 2015;
1850:1855-61. [PMID:
26025636 DOI:
10.1016/j.bbagen.2015.05.018]
[Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/21/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND
Actin filament bundling proteins mediate numerous processes in cells such as the formation of cell membrane protrusions or cell adhesions and stress fiber based locomotion. Among them alpha-actinin and fascin are the most abundant ones. This work characterizes differences in molecular motions in actin filaments due to the binding of these two actin bundling proteins.
METHODS
We investigated how alpha-actinin and fascin binding modify the conformation of actin filaments by using conventional and saturation transfer EPR methods.
RESULTS
The result characteristic for motions on the microsecond time scale showed that both actin bundling proteins made the bending and torsional twisting of the actin filaments slower. When nanosecond time scale molecular motions were described the two proteins were found to induce opposite changes in the actin filaments. The binding of one molecule of alpha-actinin or fascin modified the conformation of numerous actin protomers.
CONCLUSION
As fascin and alpha-actinin participates in different cellular processes their binding can serve the proper tuning of the structure of actin by establishing the right conformation for the interactions with other actin binding proteins. Our observations are in correlation with the model where actin filaments fulfill their biological functions under the regulation by actin-binding proteins.
GENERAL SIGNIFICANCE
Supporting the general model for the cellular regulation of the actin cytoskeleton we showed that two abundant actin bundling proteins, fascin and alpha-actinin, alter the conformation of actin filaments through long range allosteric interactions in two different ways providing the structural framework for the adaptation to specific biological functions.
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