A Special Proton Pump

In areas with a higher proton concentration gradient, the Proton Pyrophosphatase pump moves hydrogen ions downhill. Click for more detail.

Just like other pumps, the Proton Pyrophosphatase pump usually moves hydrogen ions uphill. It gets its energy to do this by breaking down molecules known as pyrophosphates into two smaller phosphate molecules.

However, if the pump is in an area where the concentration gradient is too high, with too many hydrogen ions on one side, the pump works in the opposite direction. There, the pump moves ions downhill, and it combines two phosphate molecules into one molecule of pyrophosphate. Here, pyrophosphate can be used to make energy (ATP). Energy can then be used by a stronger proton pump to move protons out and make a stronger gradient.

A Prized Pump

One of the effects of this is that more sugars end up being passed into neighboring cells. Sugars are needed for plant growth, so in effect, this helps move sugars around the plant without using more materials than normal.

As sugars move into the roots of plants, they create more root hairs, which enables the plant to better absorb phosphate. Click to enlarge.

To use this to our benefit, scientists have modified some plants to have more of these special Proton Pyrophosphatase pumps. These plants can supply extra sugars to different tissues. This makes the plants grow longer roots (which are good for absorbing nutrients like phosphorus) and grow more leafy tissues as well. So with a boost of these pumps, we can easily have larger plants that can make more fruits.

As there may be a phosphate shortage in the near future, a boost like this could be very important for growing crops.