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A protein that makes you do the twist



Myosin 1
D molecular motor creates asymmetry at all levels, from the movement of actin molecules (red and green filaments) to the respiratory trachea ( white tube structures), at the same organism (here a larva of Drosophila). Credit: Photo of larva: Gaëlle Lebreton; photo editing by Stéphane Noselli / iBV / CNRS

The asymmetry plays an important role in biology at every scale: think of the spirals of DNA, the fact that the human heart is positioned on the left, our preference to use our left or right hand … team of the Valrose Biology Institute (CNRS / Inserm / Université Côte d'Azur), in collaboration with colleagues from the University of Pennsylvania, demonstrated how a single protein induces a spiral motion in a & # 39; other molecule. Through a domino effect, this causes the rotation of cells, organs and the whole body, triggering a lateralized behavior. This research was published in the journal Science on November 23, 2018.

Our world is fundamentally asymmetric: we think of the double helix of DNA, the asymmetric division of stem cells or the fact that the human heart is positioned on the left. But how do these asymmetries emerge and are connected to each other?

At the Valrose Institute of Biology, a team led by CNRS researcher Stéphane Noselli, which also includes researchers from Inserm and the Cote d'Azur University, has studied well – left asymmetry for several years in order to solve these puzzles. Biologists had identified the first gene that controls asymmetry in the common fruit fly (Drosophila), one of the biologically preferred model organisms. More recently, the team has shown that this gene has the same role in vertebrates: the protein that it produces, Myosin 1D, controls the rotation or rotation of the organs in the same direction.

In this new study, the researchers induced myosin 1D production in the normally symmetrical organs of Drosophila, such as the respiratory trachea. Somewhat spectacular, this was enough to induce asymmetry at all levels: deformed cells, wind-trachea, self-twisting, and helical locomotor behavior between fly larvae. Surprisingly, these new asymmetries always develop in the same direction.




The movement of a normal larva (left) and a larva that express myosin 1D in its normally symmetrical epidermis. While the normal larva crawls linearly, with its ventral side in contact with the liquid, the modified larva is twisted and moves through the directional "cylindrical rollers". Credit: Gaëlle Lebreton / iBV / CNRS

To identify the origin of these cascading effects, even the University of Pennsylvania biochemists contributed to the project: on a coverslip they brought Myosin 1D into contact with a component of the cytoskeleton ("the backbone" of the cell), that is to say actin. They were able to observe that the interaction between the two proteins caused the actin spiral.

In addition to its role in left-to-right asymmetry between Drosophila and vertebrates, myosin 1D appears to be a unique protein capable of inducing asymmetry per se at all scales, first at the molecular level, then, through a domino effect, at the cellular, tissue and behavioral level. These results suggest a possible mechanism for the sudden appearance of new morphological characteristics in the course of evolution, such as, for example, the torsion of the bodies of snails. Myosin 1D therefore seems to have all the characteristics necessary for the emergence of this innovation, since its sole expression is sufficient to induce torsion on all scales.


Explore further:
Atomic resolution of muscle contraction

Further information:
"Molecular-organismic chirality is induced by conserved myosin 1D" Science (2018). science.sciencemag.org/cgi/doi … 1126 / science.aat8642

Journal reference:
Science

Provided by:
CNRS


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