#elastin

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The stretchiness that allows living tissues to expand, contract, stretch, and bend throughout a lifetime is the result of a protein molecule called tropoelastin. Remarkably, this molecule can be stretched to eight times its length and always returns back to its original size.

Now, for the first time, researchers have decoded the molecular structure of this complex molecule, as well as the details of what can go wrong with its structure in various genetically driven diseases.

Tropoelastin is the precursor molecule of elastin, which along with structures called microfibrils is the key to flexibility of tissues including skin, lungs, and blood vessels. But the molecule is complex, made up of 698 amino acids in sequence and filled with disordered regions, so unravelling its structure has been a major challenge for science.

Stretchy Simulations

We all lose that youthful glow over time, partly because of diminishing elastin levels. This protein doesn't just give us great-looking skin, it enables many tissues to stretch and contract, including our lungs and arteries. Elastin works by forming fibres that weave around our tissues, which are also bathed in water. These fibres form when elastin aggregates, though how wasn’t entirely clear. Researchers investigated how using computer simulations (pictured) of the hydrophobic domains contained within elastin. These domains don’t like water but are central to elastin’s stretchy abilities. A common way to shield hydrophobic domains from water is to bury them deep within proteins in structures called hydrophobic cores. However simulations revealed elastin-like proteins don't do this. Quite the opposite; water (cyan) is spread throughout the elastin aggregates. Nonetheless, careful construction keeps the hydrophobic domains (yellow) conveniently away from all that water, revealing the molecular details of elastin’s stretchiness.

Written by Lux Fatimathas

Image from work by Sarah Rauscher and Régis Pomès

Molecular Medicine, The Hospital for Sick Children, Toronto, Canada

Image originally published under a Creative Commons Licence (BY 4.0)

Published in eLife, November 2017