ABSTRACT
Diatoms often outnumber other eukaryotic algae in the oceans, especially in coastal environments characterized by frequent fluctuations in light intensity. The identities and operational mechanisms of regulatory factors governing diatom acclimation to high light stress remain largely elusive. Here, we identified the AUREO1c protein from the coastal diatom Phaeodactylum tricornutum as a crucial regulator of non-photochemical quenching (NPQ), a photoprotective mechanism that dissipates excess energy as heat. AUREO1c detects light stress using a light-oxygen-voltage (LOV) domain and directly activates the expression of target genes, including LI818 genes that encode NPQ effector proteins, via its bZIP DNA-binding domain. In comparison to a kinase-mediated pathway reported in the freshwater green alga Chlamydomonas reinhardtii, the AUREO1c pathway exhibits a faster response and enables accumulation of LI818 transcript and protein levels to comparable degrees between continuous high-light and fluctuating-light treatments. We propose that the AUREO1c-LI818 pathway contributes to the resilience of diatoms under dynamic light conditions.
Subject(s)
Acclimatization , Diatoms , Light , Diatoms/metabolism , Diatoms/genetics , Diatoms/radiation effects , Chlamydomonas reinhardtii/metabolism , Chlamydomonas reinhardtii/genetics , Chlamydomonas reinhardtii/radiation effects , Algal Proteins/metabolism , Algal Proteins/genetics , Gene Expression Regulation/radiation effectsABSTRACT
Dunaliella bardawil is a marine unicellular green algal that produces large amounts of ß-carotene and is a model organism for studying the carotenoid synthesis pathway. However, there are still many mysteries about the enzymes of the D. bardawil lycopene synthesis pathway that have not been revealed. Here, we have identified a CruP-like lycopene isomerase, named DbLyISO, and successfully cloned its gene from D. bardawil. DbLyISO showed a high homology with CruPs. We constructed a 3D model of DbLyISO and performed molecular docking with lycopene, as well as molecular dynamics testing, to identify the functional characteristics of DbLyISO. Functional activity of DbLyISO was also performed by overexpressing gene in both E. coli and D. bardawil. Results revealed that DbLyISO acted at the C-5 and C-13 positions of lycopene, catalyzing its cis-trans isomerization to produce a more stable trans structure. These results provide new ideas for the development of a carotenoid series from engineered bacteria, algae, and plants.