Physical Rules Regulating Membraneless Organelles Outlined

A study published in Nature Communications explores how membraneless organelles (MLOs), form and organize themselves. The research team from the University at Buffalo studied the physical rules controlling the arrangement of various types of synthetic MLOs created using just three kinds of building materials: RNA and two different proteins, a prion-like polypeptide and an arginine-rich polypeptide.

"Different condensates can coexist inside the cells," says first author Taranpreet Kaur. "They can be detached, attached to another condensate, or completely embedded within one another. So how is the cell controlling this? We found two different mechanisms that allowed us to control the architecture of synthetic membraneless organelles formed inside a test tube. First, the amount of RNA in the mixture helps to regulate the morphology of the organelles. The other factor is the amino acid sequence of the proteins involved."

"These two factors impact how sticky the surfaces of the condensates are, changing how they interact with other droplets," says Priya Banerjee, one of two senior authors of the paper. "In all, we have shown using a simple system of three components that we can create different kinds of organelles and control their arrangement in a predictive manner. We suspect that such mechanisms may be employed by cells to arrange different MLOs for optimizing their functional output."

Their experiments were done on model systems made from RNA and proteins. "Going back to our motivations in researching MLOs, the big questions that started the field were questions in cell biology: How do cells organize their internal space?" Banerjee says. "The principles we uncover here contribute to the knowledge base that will improve understanding in this area."