From trash to stash – converting yeast lytic vacuoles into protein storage vacuoles

With the global population rising, the need to provide important proteins in food and healthcare increases. A way to produce vast amount of protein in an environmentally friendly way is an important problem that needs to be solved. Seeds are a nutritional powerhouse, and one of the reasons for this are the many protein-filled organelles called protein storage vacuoles found within seed cells. These protein storage vacuoles are essential for helping seeds germinate, and are a great resource for human protein consumption, without contributing to the environmentally damaging meat industry. These protein storage vacuoles are formed from one large lytic vacuole, which is essentially waste management centre of the cell, through droplet formation that have gone through liquid-liquid phase separation. Liquid-liquid phase separation is when two liquids co-exist within the same space and yet are separated, as seen when vinegar and oil are put together and droplets form. The proteins that undergo liquid-liquid phase separation within the seed cell vacuole are called 2S albumins and 12S globulins, two families of seed storage proteins. If these proteins are truly capable of forming droplets within the harsh environment of a vacuole through a biophysical process, they should be able to form droplets in any organism’s vacuole.

Yeast has many applications, from producing beer to being used in bread making. They have also been used as protein factories in some scenarios but not every protein can be efficiently made by yeast, if at all. If yeast vacuoles can be used to store proteins using droplet formation, any protein we want can be mass produced. For instance, if we can have yeast vacuoles with seed storage proteins inside, we will be able to mass produce a protein rich source for human consumption and with the right balance of amino acids. We could also attach the driving components of droplet formation that seed storage proteins have, to mass produce expensive and hugely desired proteins such as human serum albumin found in human blood or the brazzein protein, a sweetener.