Molecular to organismal chirality is induced by the conserved myosin 1D

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Science  23 Nov 2018:
Vol. 362, Issue 6417, pp. 949-952
DOI: 10.1126/science.aat8642

A single myosin sets chirality at all scales

When viewed externally, most organisms appear symmetric between the left and right sides. However, many organs are left-right asymmetric. Whether macroscopic asymmetries are directly related to molecular-level chirality remains an open question. Working in Drosophila, Lebreton et al. found that the conserved molecular motor myosin 1D induced stereotyped chirality at all biological scales—from F-actin turning in vitro to the organ level and even organismal behavior. Thus, a single conserved myosin can generate de novo nano-to-macroscopic changes in form and direction through chiral interaction with the actin cytoskeleton.

Science, this issue p. 949


The emergence of asymmetry from an initially symmetrical state is a universal transition in nature. Living organisms show asymmetries at the molecular, cellular, tissular, and organismal level. However, whether and how multilevel asymmetries are related remains unclear. In this study, we show that Drosophila myosin 1D (Myo1D) and myosin 1C (Myo1C) are sufficient to generate de novo directional twisting of cells, single organs, or the whole body in opposite directions. Directionality lies in the myosins’ motor domain and is swappable between Myo1D and Myo1C. In addition, Myo1D drives gliding of actin filaments in circular, counterclockwise paths in vitro. Altogether, our results reveal the molecular motor Myo1D as a chiral determinant that is sufficient to break symmetry at all biological scales through chiral interaction with the actin cytoskeleton.

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