PRIONS: ZOMBIE PROTEINS

First posted on Tumblr on 4/11/21.

So, prion diseases are freaky. Hardly covering new territory here. They are 100% fatal, cause horrifying neurodegenerative symptoms and can be transmitted in any way imaginable. Examples include mad cow disease, chronic wasting disease and scrapie, as well as Creutzfeldt–Jakob disease and fatal familial insomnia in humans.

People usually describe prions as ‘misfolded proteins’. But what I didn’t know until this morning is that almost all prions are an infectious variant of one specific protein called PrP (the imaginatively-named prion protein). PrP is highly conserved, especially among mammals, and is found all over the body but especially within the nervous system. We don’t know its function.

There are a few misfolded variants of PrP, some inherited as genetic mutations and others picked up through consumption of or exposure to infected organisms. Those misfolded variants, whenever they come into contact with healthy PrP, turn that healthy PrP into more misfolded PrP. And so the cycle continues.

Misfolded PrP is resistant to all known proteases and has extreme resistance to heat, ionizing radiation and formaldehyde. It can last for years in the soil, in water, in carcasses, in plants, on the ground… you get the gist.

While the function of PrP is unknown, its destruction and accumulation of misfolded variants causes spongy holes in nervous tissue. Problems with movement, memory, speech and sight are characteristic.. It feels like this is an area with a lot left to discover, and possibly one that we can turn to our advantage if we can find a way to copy the replicative effects for the purposes of medicine.

What fascinates me most about these proteins is how closely they resemble life. Stick with me here! They self-replicate in a sense, in a similar parasitic way to viruses. However, instead of preying on the genome, they prey on proteins. If prions ever became more complex they could be well on their way to becoming the first solely protein based life form. But can such a life form exist without nucleic acid based life forms to provide it with fully formed proteins to 'turn’?

Update 19/05/2022:

The very kind neocities user and PhD candidate Leota has informed me of some mistakes in this article, so thank you for the corrections! Firstly, mutated -> misfolded, as mutated implies DNA or RNA. Secondly, I had some confusion regarding the link between prions and Alzheimer's, so I've reworded that bit. You can check the Internet Archive if you want to see the page pre-update - should be the first capture.