Role of Actin C-Terminus in Regulation of Striated Muscle Thin Filament
| Autor: | Joanna Moraczewska, Radosław Skórzewski, Masłgorzata Śliwińska |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
Protein Conformation
Muscle Fibers Skeletal Biophysics Arp2/3 complex macromolecular substances Myosins Biology Microfilament 03 medical and health sciences Actin remodeling of neurons Myosin Muscle and Contractility Actin-binding protein 030304 developmental biology 0303 health sciences Binding Sites Meromyosin Molecular Motor Proteins 030302 biochemistry & molecular biology Actin remodeling musculoskeletal system Actins Models Chemical Biochemistry biology.protein Calcium MDia1 Protein Binding |
| Zdroj: | Biophysical Journal |
| ISSN: | 0006-3495 |
| DOI: | 10.1529/biophysj.107.115055 |
| Popis: | In striated muscle, regulation of actin-myosin interactions depends on a series of conformational changes within the thin filament that result in a shifting of the tropomyosin-troponin complex between distinct locations on actin. The major factors activating the filament are Ca(2+) and strongly bound myosin heads. Many lines of evidence also point to an active role of actin in the regulation. Involvement of the actin C-terminus in binding of tropomyosin-troponin in different activation states and the regulation of actin-myosin interactions were examined using actin modified by proteolytic removal of three C-terminal amino acids. Actin C-terminal modification has no effect on the binding of tropomyosin or tropomyosin-troponin + Ca(2+), but it reduces tropomyosin-troponin affinity in the absence of Ca(2+). In contrast, myosin S1 induces binding of tropomyosin to truncated actin more readily than to native actin. The rate of actin-activated myosin S1 ATPase activity is reduced by actin truncation both in the absence and presence of tropomyosin. The Ca(2+)-dependent regulation of the ATPase activity is preserved. Without Ca(2+) the ATPase activity is fully inhibited, but in the presence of Ca(2+) the activation does not reach the level observed for native actin. The results suggest that through long-range allosteric interactions the actin C-terminus participates in the thin filament regulation. |
| Databáze: | OpenAIRE |
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