As a result of the synchrotron light techniques available at MAX IV Laboratory in Lund, Professor Adrian Goldman’s research team at the University of Helsinki was able to map the structure of a type of protein. The protein, called pyrophosphatase, is a so-called membrane protein found in plants and bacteria as well as in certain types of parasites known as protozoans. The function of the protein is crucial because it helps to maintain the correct ion balance in cells. For parasites, the ion balance is critical, allowing them to invade and live inside other organisms. Pyrophosphatases are also vital for maturation and development processes. For example, they help plants survive in stressful conditions such as drought, cold or darkness.
Pyrophosphatases are not found in mammals or humans, making them interesting for the pharmaceutical industry. Knowledge of what the protein looks like gives us important pieces of the puzzle so that we can develop the medicines of the future to fight diseases such as malaria and sleeping sickness.
“Knowledge of the structure of pyrophosphatases increases our general knowledge about membrane proteins. Despite the fact that more than 50 per cent of the pharmaceuticals on the market interact with membrane proteins, we have a very limited understanding of how they work compared to soluble proteins. For example, over 80,000 three-dimensional protein structures are known, but only 357 of these are membrane proteins”, explains Marjolein Thunnissen, responsible for the research at experimental station I911-3 at the MAX II ring of MAX IV Laboratory in Lund.
Now that researchers have described the structure of pyrophosphatases, they have discovered that their mechanism of pumping ions through the membrane is different from what we know about other classes of membrane proteins. In order for the protein to succeed in pumping ions through the cell membrane, energy is needed. Pyrophosphatase uses as its energy source a phosphate-rich molecule (pyrophosphate) which is split in the process. The splitting releases energy which allows the protein to move and pump ions through the membrane.
The action of the protein is ingenious because pyrophosphatases are a natural by-product, and when used as a source of energy, it makes the cell more efficient. Researchers from Professor Adrian Goldman’s research team at the University of Helsinki collected the data for the protein “sodium-pumping pyrophosphatases” at station I911-3 at the MAX II Ring at MAX IV Laboratory in Lund as well as at several experimental stations at ESRF in Grenoble, France.