Hybrid CCM in Thalassiosira pseudonana

Manipulated carbonate chemistry to disentangle proteins involved in the carbon concentrating mechanism (CCM) of Thalassiosira pseudonana from other cellular mechanisms that employ the same proteins. The malate/oxaloacetate shuttle shares overlap with biochemical CCMs while also supporting pH regulation, maintenance of redox poise, cyclic electron transport, and the dissipation of excess light energy. Three treatments were used to separate out the effects of pH and pCO2: low pCO2/high pH (LCHpH), high pCO2/low pH (HCLpH), and low pCO2/low pH (LCLpH). Results from this analysis were consistent with a hybrid CCM within T. pseudonana that consists of both biophysical and biochemical steps. No evidence for alternative cellular mechanisms that could explain protein abundance profiles observed under low pCO2 conditions was found.