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The molecular motor Myosin 1D creates asymmetry at all levels, from the movement of actin molecules (red and green filaments) to the respiratory trachea (white tube structures), through the organism itself. same (here a larva of Drosophila). Credit: Photo of the larva: Gaëlle Lebreton; photo edition of Stéphane Noselli / iBV / CNRS
Asymmetry plays a major role in biology at all scales: think of the spirals of DNA, the fact that the heart of man is positioned on the left, our preference for the use of our left or right hand. .. A team from the Valrose Biology Institute (CNRS / Inserm / Cote d'Azur University), in collaboration with colleagues from the University of Pennsylvania, showed how a single protein induces a spiral motion in another molecule. By a domino effect, cells, organs and even the whole body twist, causing lateralized behavior. This research is published in the journal Science November 23, 2018.
Our world is fundamentally asymmetrical: think of the double helix of DNA, the asymmetrical division of stem cells or the fact that the human heart is on the left. But how do these asymmetries emerge and are they related to each other?
At the Valrose Biology Institute, a team led by CNRS researcher Stéphane Noselli, which also includes researchers from Inserm and Université Côte d'Azur, has been studying for several years the Right-left asymmetry to solve these puzzles. Biologists had identified the first gene controlling asymmetry in the fruit fly (Drosophila), one of the biologists' favorite model organisms. More recently, the team has shown that this gene plays the same role in vertebrates: the protein it produces, myosin 1D, controls the winding or the rotation of organs in the same direction.
In this new study, the researchers induced the production of Myosin 1D in the normally symmetrical organs of Drosophila, such as the respiratory trachea. Quite dramatically, this was enough to induce asymmetry at all levels: deformed cells, tracheal windings around themselves, whole-body torsion, and helical locomotor behavior in fly larvae. Remarkably, these new asymmetries always evolve in the same direction.
In order to identify the origin of these cascading effects, biochemists from the University of Pennsylvania also contributed to the project: on a glass slide, they put Myosin 1D in contact with a component of cytoskeleton (the act), the "skeleton" of the cell. They were able to find that the interaction between the two proteins resulted in spiral actin.
In addition to its role in right-left asymmetry in Drosophila and vertebrates, myosin 1D appears to be a unique protein capable of inducing asymmetry per se at all scales, initially at the molecular level. then domino effect at the cellular, tissue and behavioral level. These results suggest a possible mechanism for the sudden onset of new morphological features during evolution, such as, for example, body twisting of snails. Myosin 1D therefore seems to possess all the characteristics necessary for the appearance of this innovation, its expression alone being able to induce a twist at all scales.
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More information:
"Molecular chirality to the body is induced by the preserved 1D myosin" Science (2018). science.sciencemag.org/cgi/doi… 1126 / science.aat8642
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