A. Madhushika Silva - January 15

Role of amino acid substitutions in Atlantic salmon tropomyosin

Tropomyosin is an alpha helical coiled coil dimeric protein having a regulatory role in the thin filament of striated muscle. It is highly conserved. For example, tropomyosin from the fast contracting (light-toned) trunk muscle of Atlantic salmon (Salmo salar) contains just 20 amino acid differences (> 92% identity) compared to the homologue in mammals. Yet Salmo salar thrives at temperatures that are near freezing. How is the protein in salmon able to maintain sufficient flexibility to function under such conditions? The answer must reside in changes to its amino acid sequence. In this regard, the role of only charge substitution; res 77 (Thr salmon; Lys rabbit) has been investigated by mutation and analysis of the known biochemical properties of tropomyosin specifically the conformational stability of the coiled coil (as analyzed by limited proteolysis and calorimetry) and the interaction with F-actin.



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