#myosin

Kengan M - Evidence

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Dis-banded

Just like us, fruit flies are stripy beneath the skin. These sarcomeres – repeating bands of stretchy muscle tissue – contain fibres of myosin (highlighted in green) and actin (purple) griping and pulling at each other – as the sarcomeres shorten, the muscle contracts. This is heart muscle from fruit flies (Drosophila), used to investigate common faults in human heart disease. Compared to healthy muscle at the top, the sarcomeres at the bottom are much looser and swollen – in these hearts, researchers used RNA interference to hamper the activity of a protein called filamin, often shown to be altered in heart diseases like hypertrophic cardiomyopathy. Yet altering its activity in a different way – using CRISPR gene editing to change its structure – did not affect the flies as expected. Further studies might aim to solve this mystery, while altering genes and proteins reveals more about what we do, or perhaps don’t, have in common with Drosophila.

Written by John Ankers

Image from work by Flavie Ader and colleagues

Université Paris Cité, Paris, France

Image originally published with a Creative Commons Attribution – NonCommercial – NoDerivs (CC BY-NC-ND 4.0)

Published in Biology Open, September 2022

Atomic resolution of muscle contraction

At the molecular level, muscle contraction is defined by myosin molecules pulling actin filaments. New electron cryomicroscopy images with unprecedented resolution taken by researchers at Osaka University reveal unexpectedly large conformational changes in the myosin molecule during the pull. These findings, which can be seen in Nature Communications, provide new insights into how myosin generates force and a paradigm for the construction of nanomachines.

Takashi Fujii, Keiichi Namba. Structure of actomyosin rigour complex at 5.2 Å resolution and insights into the ATPase cycle mechanism. Nature Communications, 2017; 8: 13969 DOI: 10.1038/ncomms13969