Japanese researchers discover “switch” in algae impacting starch levels

In Japan, results from a collaborative study by Tokyo Tech and Tohoku University, Japan, raise prospects for large-scale production of algae-derived starch, a valuable bioresource for biofuels and other renewable materials. Such bio-based products have the potential to replace fossil fuels and contribute to the development of sustainable systems and societies.

A “switch” controlling the level of starch content in algae has been discovered by a research team led by Sousuke Imamura at the Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Tech.

Reported in The Plant Journal, the study focused on the unicellular red alga Cyanidioschyzon merolae. The researchers demonstrated that starch content could be dramatically increased in C. merolae through inactivation of TOR (target of rapamycin), a protein kinase1 known to play an important role in cell growth.

They observed a notable increase in the level of starch 12 hours after inactivation of TOR through exposure to rapamycin, and this led to a remarkable ten-fold increase after 48 hours.

Importantly, the study details a mechanism underlying this profound increase in starch content. Using a method called liquid chromatography-tandem mass spectrometry (LC-MS/MS), the researchers examined subtle changes in the structure of more than 50 proteins that might be involved in “switching on” the process of starch accumulation. As a result, they pinpointed GLG1 as a key protein of interest. GLG1 acts in a similar way to glycogenin, an enzyme found in yeast and animal cells, which is known to be involved in the initiation of starch (or glycogen) synthesis.

The mechanism will be of immense interest to a wide range of industries seeking to scale up biofuel and value-added biochemicals production.