FIGURE 5.

Proposed model of lipid homeostasis via alka(e)ne biodegradation in cyanobacteria under high light. ROS accumulate significantly under high light, which leads to membrane lipid damage (represented as the red lines close to “Damage”) and changes in the iron valence in the ADO active center to form the Fe^IV superoxo species. Then, the ADO with Fe^IV superoxo species will convert the alka(e)nes (represented as green sphere) to the corresponding aldehydes, which will be catalytically converted to fatty acids by ALDH. The resulting fatty acids will support membrane lipid homeostasis under oxidative stress. Highly reduced alka(e)nes can serve as electron sinks for maintaining redox homeostasis in cyanobacteria. Under high light, alka(e)nes can act as electron donors to reduce the partially reduced ROS.