Amyloid Can Explain the Origin of Life, Despite Its Disease-Causing Reputation

On the amyloid paradox (Part I)

Prebiotic Earth landscape with volcanic activity and lightning. AI-generated image with DALL·E.

Before amyloids became infamous as the toxic plaques that cause diseases like Alzheimer’s disease and amyloidoses, they may have helped life itself take root and propagate on Earth. Yet, in an apparent act of betrayal by evolution, these amyloids somehow turned against us. Why?

As I find it too ambitious to answer this paradox in a single article, I’ve decided to separate it into a three-part series:

1. The role of amyloids in catalyzing the emergence of life.

2. How amyloids supported the survival of early microbial life.

3. Why amyloids, once lifesavers, become agents of diseases.

While part 1 may not be an easy read since it involves complex evolutionary biochemistry, I’ve done my best to articulate the ideas in my own succinct structure. Much of this article is based on the pioneering work of scientists from three leading institutions: the University of Helsinki in Finland, Tel Aviv University in Israel, and ETH Zürich in Switzerland.

The Amyloid World Hypothesis

Let’s go back to about 4 billion years ago when the Earth was just a prebiotic (biotic means life) soup consisting of simple chemicals like water, methane, ammonia, and hydrogen. These chemicals are believed to have reacted with the energy from lighting, sunlight, or volcanoes to produce organic compounds, such as amino acids and nucleotides. (Organic compounds refer to carbon-containing compounds that form the basis of life)

Over time, these small molecules joined together to form larger, more complex structures. Amino acids joined to form peptides and proteins, which can perform basic chemical reactions. Nucleotides bonded to form RNA and DNA, which can store information. Eventually, these complex structures combined and evolved further to give rise to the first living cells.

But these processes were far from easy, given the harsh conditions on early Earth. With surface temperatures ranging from 85°C to 110°C (185°F to 230°F), any newly formed peptides or nucleotides would have faced rapid degradation. Frequent lightning storms, volcanic activities, and cosmic radiation further made early Earth inconducive to life.

Yet, life managed to form at that time. But how?