Figure 1

Selected key reactions of linear and alternate electron flow pathways in Synechocystis sp. PCC 6803 contained in the RN and GN model. Dashed arrows with H ⁺ represent release or pumping of protons into the thylakoid lumen. The resulting proton motive force is then used for ATP synthesis via ATPase. The two boxes at the bottom (right) display ATP and NADPH stoichiometries of electron flow pathways and for biomass and ethanol synthesis. Abbreviations: PSI/PSII: photosystem I and II, Cyt b ₆ f: cytochrome b ₆ f, Cox: cytochrome c oxidase, Cyd: cytochrome bd-type quinol oxidase, FNR: ferredoxin NADP reductase, ATPase: ATP synthase, FQR: ferredoxin quinone reductase, NDH I: NADPH dehydrogenase I, PQ: plastoquinone, PC: Plastocyanin, Fd: Ferredoxin, LEF: linear electron flow, CEF: cyclic electron flow, AEF: alternate electron flow, e ^-: electrons.