Beyond Disease: How Amyloid Shaped Early Life Across All Three Domains of Life

On the amyloid paradox (Part II)

Deep-sea hydrothermal vents. AI-generated image with DALL·E.

In the chaotic environment of early Earth about 3.9 billion years ago, several scientists believe amyloid fibrils might have aided the emergence of life by shielding fragile molecules to allow evolution to progress. But their story didn’t end there. As life transitioned into microbial forms, amyloid fibrils continued to support their survival and evolution to this day.

To recap, amyloids are proteins with stable β-sheet structures, which can self-assemble into resilient fibrils as the β-sheet stacks and interlocks. As a result, amyloid fibrils are very resilient and capable of resisting heat and chemical degradation. Today, amyloid fibrils are widely known as toxic plaques causing diseases like Alzheimer’s disease and amyloidosis.

But how did these ancient structures not only (part I) likely catalyze the emergence of life but also (part II) help early microbes thrive despite their (part III) disease-causing nature in humans?

This is part II of the amyloid paradox: what evolution reveals about amyloids and why they turn against us. Specifically, part II explores how all three domains of life (archaea, bacteria, and eukarya) capitalized on or co-opted amyloid fibrils for their survival and adaptation. Read part I here.