Prions and Viroids

We have seen how a bit of RNA or DNA and some proteins hijack our cells turning them into viral factories. Stranger still are prions and viroids. These proteins and RNA sequences infiltrate our or plants cells and wreak havoc by converting other proteins to their side or by silencing important genes. Before jumping straight into the content I want to mention that this information borders on trivia. We need to know it but don’t sweat understanding the exact mechanism of how these particles work or specific details about them.

Prions: Infectious Protiens

Prions are infectious proteins that cause other proteins to misfold simply by interacting with them. Usually, they convert ⍺-helical structures into β-pleated sheets which are far less soluble. As a result, proteins begin to aggregate and eventually inhibit normal celullar proceses.

Prions are the causative agent in mad cow disease. Since it is transmissible to humans and from cow to cow legislator banned the feeding of cow meat to livestock in order to prevent the spread of the disease.

Viroids: Gene Silencer

Viroids are tiny circular RNA sequences that bind and silence genes in plants. When these viroids affect vital genes the synthesis of life-sustaining proteins is significantly reduced or eliminated. As a result viroids can kill plants by preventing them from creating protein substrates necessary to sustain life.