Discovery of ultrafast myosin, its amino acid sequence, and structural features | Hacker News Reader

Discovery of ultrafast myosin, its amino acid sequence, and structural features

pnas.org

Myosin is a very cool protein because it’s a physical and direct link between the microscopic world of atoms and electrical charges and the macroscopic world of moving bodies.

How myosin and other protein machines work at the atomic level is actually pretty well-known! [1] Myosin and its partner actin use the same biophysical principles, such as hydrogen binding and protein conformational change, as other proteins. But whereas other proteins typically act on the scale of atoms (doing things we think of as “chemistry”, such as making or breaking chemical bonds), myosins and other molecular machines are directly and physically responsible for the macro-scale movements of beating wings, walking legs, and beating hearts.

On the subject of molecular machines: it’s sometimes asked why biology doesn’t use the wheel. Protein machines like ATP synthase [2] (which creates the ATP used by myosin to create movement) provide an answer

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6618170/

2. https://pubmed.ncbi.nlm.nih.gov/7704582/

Professor Lue from Harvard has a pretty cool visualization of how ATP synthase uses rotation and the energy produced through cellular respiration to produce ATP at https://www.youtube.com/watch?v=kXpzp4RDGJI, slightly more visceral than digging through a paper for a layperson.

Thank you for posting this link. The video does a very good job of connecting the molecular details (even down to the geometry of a transition state structure) to the macro-scale movements of ATP synthase

Throughout my biophysics phd motor proteins were a big topic in adjacent labs. Myosin was originally the one everybody was going to focus on, but the structural biophysics were challenging (for a long time the only model was a C-alpha structure in the PDB). Many people switch to kinesin, which seems to be easier to study (other grad students built their own microscopes that could track single molecules of fluorescently labelled kinesin moving around on a tiny slide). Last I had checked most of them were pretty confident the basic principles of kinesin had been worked out, but I dont think that means we can do any sort of arbitrary molecular engineering using kinesin as a motor.

Motor proteins are so incredibly cool. Like many others I was blown away by the 3D animated Inner Life of the Cell[1] showing these proteins physically walking around in the cell. Previously I had this idea that cells were just blobs of jelly and somehow they interacted with each-other to produce macro phenomena like muscle movement.

And then you get into the other protein machines like the ATP synthase in the mitochondria [2] (also linked below) which are actually little motors/pumps. And we all have billions of these inside use spinning away. It's just amazing.

1. https://youtu.be/wJyUtbn0O5Y?t=80 2. https://www.youtube.com/watch?v=kXpzp4RDGJI

> the 3D animated Inner Life of the Cell[1] showing these proteins physically walking

Reality is even more interesting. The animation regrettably prioritizes "art" over accuracy and education/misconceptions. Between one "step" and the next, the kinesin "legs" are violently flailing around, and the payload has time to explore the entire configuration space reachable given the tether. Think not of a donkey towing a barge, but of a mouse, its tail tied to a balloon, clinging to a wire, in a hurricane! The nanoscale atomic mosh pit from hell. And IIRC, the "steps" are often backward - forward is merely net more frequent. "Art"... basically "video frames" have been highly selected to tell a bogus narrative, without even a brief hint of a reality check. It's like editing a video of some politician jogging to show unmoving legs and divine levitation. Nanoscale reality is much more fun.

What are myosins?

“ Myosins are motor proteins that convert chemical energy, ATP, to physical force to move actin filaments. Phylogenetic analyses of myosin motor domain (MD) sequences have shown that there are at least 79 myosin classes, with several subclasses under each class.”

https://en.wikipedia.org/wiki/Myosin

What could be the possible applications of this?

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