Quantitative proteomic analysis of thylakoid from two microalgae (Haematococcus pluvialis and Dunaliella salina) reveals two different high light-responsive strategies

Abstract

Under high light (HL) stress, astaxanthin-accumulating Haematococcus pluvialisand β-carotene-accumulating Dunaliella salinashowed different responsive patterns. To elucidate cellular-regulating strategies photosynthetically and metabolically, thylakoid membrane proteins in H. pluvialisand D. salinawere extracted and relatively quantified after 0 h, 24 h and 48 h of HL stress. Proteomic analysis showed that three subunits of the cytochrome b6/fcomplex were greatly reduced under HL stress in H. pluvialis, while they were increased in D. salina. Additionally, the major subunits of both photosystem (PS) II and PSI reaction center proteins were first reduced and subsequently recovered in H.pluvialis, while they were gradually reduced in D. salina. D. salinaalso showed a greater ability to function using the xanthophyll-cycle and the cyclic photosynthetic electron transfer pathway compared to H. pluvialis. We propose a reoriented and effective HL-responsive strategy in H. pluvialis, enabling it to acclimate under HL. The promising metabolic pathway described here contains a reorganized pentose phosphate pathway, Calvin cycle and glycolysis pathway participating in carbon sink formation under HL in H. pluvialis. Additionally, the efficient carbon reorientation strategy in H. pluvialiswas verified by elevated extracellular carbon assimilation and rapid conversion into astaxanthin.