Fig. 3: The increases of 13C-labeled RuBisCO substrate precursors in Δxpk after transition to darkness.
From: An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria
Three WT and the three Δxpk cell cultures were grown under constant light (top) or different L/D conditions (middle and bottom) until OD730 reached 1. Equal amount of NaH13CO3 was added to the WT and Δxpk cultures in the middle of the light as 0 min (arrow) immediately before the light was turned off (black bar). a, XPK substrates (F6P, Xu5P and S7P) are RuBisCO substrate precursors. Sugar phosphates (G6P, G1P and Ru5P) are derived from F6P and Xu5P. b, XPK products and their derived compounds. G3P is a catalyzed product by XPK. 3PG, 2PG and AcCoA are intermediates and products in glycolysis. The 13C-labeled % was analyzed as the % of 13C / 12C. The 13C-labeled and unlabeled 12C-metabolites were analyzed by multiple reaction monitoring using LC–MS/MS, as described in Methods. The sum of the peak area from the 13C-labeled metabolite (13C) was divided by the total peak area consisting of the area from the unlabeled 12C metabolite (12C) and the sum area from labeled 13C. n = 3 biological repeats, mean ± s.e.m. Gray (WT) and orange (Δxpk) dots represented individual data points. Asterisk indicated significant difference between the WT and the Δxpk using one-sided statistical t-test via one-way analysis of variance (ANOVA). *P < 0.05 and **P < 0.01.
