Tree and amino acid alignments of thioredoxin, glucose-6-phosphate dehydrogenase, and malate dehydrogenase

Redox regulation in phytoplankton is critical to monitor and stabilize metabolic pathways under changing environmental conditions. In plastids, the thioredoxin (TRX) system is linked to photosynthetic electron transport and fine tuning the metabolism to fluctuating light levels. Expansion of the number of redox signal transmitters and their protein targets, as seen in plants, is believed to increase cell robustness. In this study, we searched for genes related to redox regulation in the genome of the photosynthetic amoeba Paulinella micropora KR01 (hereafter, KR01). The genus Paulinella includes testate filose amoebae, in which a single clade acquired a photosynthetic organelle, the chromatophore, from an alpha cyanobacterial donor. This independent primary endosymbiosis occurred relatively recently (~ 124 Ma), when compared to Archaeplastida (> 1 Ga), making photosynthetic Paulinella a valuable model for studying the earlier stages of primary endosymbiosis. Our comparative analysis ...