Pseudophosphatase STYX diversifies F-Box protein function

Enzymes are typically proteins whose task is to accelerate chemical reactions and are thereby involved in all functions in the body. Enzymes have a so-called catalytic center, which they need to bind and modify other molecules. In the course of evolution, enzymes have emerged that have a mutation in the catalytic center, which means that these enzymes can no longer perform their original job. The question now arises as to why a cell would even need these "broken" so-called pseudoenzymes. The interesting thing about this is that these pseudoenzymes are by no means useless. The fact that their catalytic center is broken actually allows them to fulfill new biological functions. In fact, pseudoenzymes have a much wider range of effects than classical enzymes. In our project, we will examine the function of one of these pseudoenzymes, namely STYX, more closely. We have found that STYX has the ability to affect the function of so-called F-box proteins. These F-box proteins decide which other proteins should be broken down in a cell. A cell has many different proteins and not all of them are always needed at the same time. Therefore, the cell needs a way to get rid of molecules that it no longer needs. When an F- box protein wants to break down another molecule, it will first bind to it and bring it to a larger protein complex, where this protein is then marked for disposal and then broken down. It is precisely this step that is prevented by STYX, as it prevents the F-box protein from reaching the larger complex. In this project, we now want to examine the interaction between STYX and the F-box protein FBXO31 in more detail. Our theory is that STYX binds to the F-box protein FBXO31, which means that FBXO31 can suddenly fulfill completely different functions in the cell that have nothing to do with the breakdown of proteins. We have evidence that STYX is involved in controlling cell division. We now want to find out exactly how this interaction between STYX and FBXO31 works and how it affects the function of the cells.