The impact of tropomyosins on actin filament assembly is isoform specific
| Autor: | Peter W. Gunning, Irina Dedova, Teresa T. Bonello, Alex Byun, Till Böcking, Miro Janco, Helene Lebhar, Adelle C.F. Coster |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Gene Expression Arp2/3 complex Tropomyosin macromolecular substances Filamentous actin Polymerization 03 medical and health sciences 0302 clinical medicine Structural Biology Escherichia coli Animals Humans Protein Isoforms Amino Acid Sequence Actin-binding protein Cloning Molecular Cytoskeleton Binding Sites Sequence Homology Amino Acid biology Actin remodeling Exons Cell Biology General Medicine Actin cytoskeleton Actins Recombinant Proteins Rats Cell biology Molecular Weight Actin Cytoskeleton Alternative Splicing Kinetics 030104 developmental biology Profilin biology.protein MDia1 Sequence Alignment 030217 neurology & neurosurgery Research Paper Protein Binding |
| Zdroj: | BioArchitecture. 6:61-75 |
| ISSN: | 1949-100X 1949-0992 |
| DOI: | 10.1080/19490992.2016.1201619 |
| Popis: | Tropomyosin (Tpm) is an α helical coiled-coil dimer that forms a co-polymer along the actin filament. Tpm is involved in the regulation of actin's interaction with binding proteins as well as stabilization of the actin filament and its assembly kinetics. Recent studies show that multiple Tpm isoforms also define the functional properties of distinct actin filament populations within a cell. Subtle structural variations within well conserved Tpm isoforms are the key to their functional specificity. Therefore, we purified and characterized a comprehensive set of 8 Tpm isoforms (Tpm1.1, Tpm1.12, Tpm1.6, Tpm1.7, Tpm1.8, Tpm2.1, Tpm3.1, and Tpm4.2), using well-established actin co-sedimentation and pyrene fluorescence polymerization assays. We observed that the apparent affinity (Kd(app)) to filamentous actin varied in all Tpm isoforms between ∼0.1-5 μM with similar values for both, skeletal and cytoskeletal actin filaments. The data did not indicate any correlation between affinity and size of Tpm molecules, however high molecular weight (HMW) isoforms Tpm1.1, Tpm1.6, Tpm1.7 and Tpm2.1, showed ∼3-fold higher cooperativity compared to low molecular weight (LMW) isoforms Tpm1.12, Tpm1.8, Tpm3.1, and Tpm4.2. The rate of actin filament elongation in the presence of Tpm2.1 increased, while all other isoforms decreased the elongation rate by 27-85 %. Our study shows that the biochemical properties of Tpm isoforms are finely tuned and depend on sequence variations in alternatively spliced regions of Tpm molecules. |
| Databáze: | OpenAIRE |
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