Movement is one of the fundamental properties of living organisms. In most animals, movement is powered by contraction of striated muscles, so called because of their highly regular and repetitive organization of protein filaments that are seen as striations under a microscope. All striated muscles contain thick filaments whose main component is myosin, the evolutionarily conserved motor protein responsible for generating the force for muscle contraction. Thick filaments from different muscle types have distinct structural and mechanical properties that are imparted by non-myosin thick filament proteins. Thus, these proteins play a significant role in defining functional differences among muscle types. This research will address the functions of flightin, a novel thick filament protein that is essential for the structural integrity and mechanical stability of the flight muscle in the fruit fly, Drosophila melanogaster. Specifically, this project aims to elucidate the molecular interaction between flightin and myosin through a combination of in vitro biochemical studies and in vivo genetic approaches. A key hypothesis of this work is that a conserved amino acid region in flightin (of approximately 52 amino acids) identifies a new myosin binding domain that is widespread among two major groups of invertebrates, the insects and the crustaceans. To elucidate the structural basis of flightin function, a detailed three dimensional model of the thick filament from the fruit fly flight muscle will be generated by tomography from images obtained with an electron microscope. A combination of molecular labeling techniques and comparison of filament structures with and without flightin will result in the identification and localization of flightin in the thick filament. These studies will provide the first higher resolution three-dimensional structure of thick filaments from a model genetic organism and will provide the foundation for the structural analysis of a plethora of Drosophila melanogaster flight muscle mutants with known genetic, biochemical, and mechanical defects. Additionally, the impact of this research will extend to areas of evolutionary biology and phylogenetics that seek to understand the diversification of life forms as exemplified by the insects, arguably the most successful group of animals.
Broader impacts This research will have impacts in the areas of education and the generation of biological reagents for the Drosophila and muscle research communities. Previous NSF funding to this research group has been instrumental in training undergraduate and graduate students, including members from underrepresented groups and disadvantaged backgrounds, and this project is designed to integrate research with continuing educational opportunities. Knowledge generated from this research will find its way to advanced undergraduate and graduate specialty courses, review articles and book chapters intended for the research community, and articles and stories for the non-scientific audience. Results will be broadly disseminated through our website, publications in peer-reviewed journals, and by undergraduate and graduate students who will present their work at scientific meetings. All reagents (DNA clones, mutant and transgenic strains) will be freely available to other investigators.
