Which pair of elements shall affect both photosynthetic and mitochondrial electron transport?

Cu and Fe participate in electron transport chain during photosynthesis. Plastocyanine is a copper protein that transfers electrons from cytochrome f to P700. Cytochrome - c oxidase is also a copper protein (complex IV) which is involved in respiration. Cytochromes are iron containing compounds which are involved in electron transport system in both chloroplast and mitochondria.