Friday , November 27 2020

A twisting protein

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

Asymmetry plays an important role in biology in every scale: thinking of DNA spirals, positioning the human heart on the left, choosing our left or right hand … Biology is a team from the Valrose Institute (CNRS) / Inserm / Université Côte d 'Azur In collaboration with colleagues from the University of Pennsylvania, he demonstrated how a single protein causes spiral movement in another molecule. Through a domino effect, it triggers lateral behaviors, bending cells, organs and actually the whole body. This research was published in the journal Science November 23, 2018.

Our world is basically asymmetric: consider the double helix of the DNA, the asymmetrical division of the stem cells, or the human heart positioned to the left. But how do these asymmetries emerge and how do they relate to each other?

The Valve Institute of Biology, led by Stéphane Noselli, a researcher at Inserm and Université Cote d'alle, including Azur researchers, examines the left-right asymmetry of several years to solve these riddles. Biologists have identified the first gene control asymmetry in the common fruit fly (Drosophila), one of the preferred model organisms of biologists. More recently, the team has shown that this gene plays the same role in vertebrates: the protein it produces, Myosin 1D, controls the rounding or rotation of organs in the same direction.

In this new study, the investigators initiated the production of Myosin 1D in normal symmetric organs of Drosophila, such as the respiratory trachea. Quite strikingly, this was enough to induce asymmetry at all levels: deformed cells, trachea wrapped around itself, curvature of the whole body, and helicopter behavior between the fly larvae. Remarkably, these new asymmetries always develop in the same direction.

A normal larval movement in a normal symmetrical epidermis (left) and a larval movement expressing Myosin 1D. When the normal larvae are linearly in contact, the ventral side is in contact with the fluid, while the modified larvae are bent and oriented to the & # 39; barrel rolls & # 39; moves with. Credit: Gaëlle Lebreton / iBV / CNRS

To determine the origin of these cascading effects, biochemists from the University of Pennsylvania also contributed to the project: on a glass coverslip, Myosin brought the 1D into contact with a cell skeleton (the cell's "backbone"), ie actin. They observed that the interaction between the two proteins caused the actin to spiral.

In addition to its role in right-left asymmetry between Drosophila and vertebrates, Myosin 1D appears to be a unique protein that can induce asymmetry on its own and at any scale, at first, at the molecular level, then by the domino effect. cell, tissue and behavior level. These results illustrate a possible mechanism for the sudden emergence of new morphological features during evolution, such as bending of snail bodies. Myosin 1D appears to have all the features necessary for the expression of this expression, since the expression alone is sufficient to induce bending at all scales.

Explore more:
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More information:
"Molecularly protected myosin is induced by 1D to organized terrain" Science (2018). 1126 / science.aat8642

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