Tropomyosin-binding properties modulate competition between tropomodulin isoforms.
The formation and fine-tuning of cytoskeleton in cells are governed by proteins that influence actin filament dynamics. Tropomodulin (Tmod) regulates the length of actin filaments by capping the pointed ends in a tropomyosin (TM)-dependent manner. Tmod1, Tmod2 and Tmod3 are associated with the cytoskeleton of non-muscle cells and their expression has distinct consequences on cell morphology. To understand the molecular basis of differences in the function and localization of Tmod isoforms in a cell, we compared the actin filament-binding abilities of Tmod1, Tmod2 and Tmod3 in the presence of Tpm3.1, a non-muscle TM isoform. Tmod3 displayed preferential binding to actin filaments when competing with other isoforms. Mutating the second or both TM-binding sites of Tmod3 destroyed its preferential binding. Our findings clarify how Tmod1, Tmod2 and Tmod3 compete for binding actin filaments. Different binding mechanisms and strengths of Tmod isoforms for Tpm3.1 contribute to their divergent functional capabilities.
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States. Electronic address: mert.colpan@wsu.edu.
Mert
M
Colpan
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States.
Natalia A
NA
Moroz
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States.
Kevin T
KT
Gray
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States.
Dillon A
DA
Cooper
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States.
Christian A
CA
Diaz
Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-6515, United States. Electronic address: alla.kostyukova@wsu.edu.
Alla S
AS
Kostyukova
D001665:Binding Sites; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D051348:Tropomodulin / Q000737:chemistry* / Q000648:ultrastructure*; D014335:Tropomyosin / Q000737:chemistry* / Q000648:ultrastructure*
D020033:Protein Isoforms; D051348:Tropomodulin; D014335:Tropomyosin
Actin; Cytoskeleton; Tropomodulin; Tropomyosin