ジャーナル: Nat Metab / 年: 2023 タイトル: An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria. 著者: Kuan-Jen Lu / Chiung-Wen Chang / Chun-Hsiung Wang / Frederic Y-H Chen / Irene Y Huang / Pin-Hsuan Huang / Cheng-Han Yang / Hsiang-Yi Wu / Wen-Jin Wu / Kai-Cheng Hsu / Meng-Chiao Ho / Ming-Daw ...著者: Kuan-Jen Lu / Chiung-Wen Chang / Chun-Hsiung Wang / Frederic Y-H Chen / Irene Y Huang / Pin-Hsuan Huang / Cheng-Han Yang / Hsiang-Yi Wu / Wen-Jin Wu / Kai-Cheng Hsu / Meng-Chiao Ho / Ming-Daw Tsai / James C Liao / 要旨: Regulation of CO fixation in cyanobacteria is important both for the organism and global carbon balance. Here we show that phosphoketolase in Synechococcus elongatus PCC7942 (SeXPK) possesses a ...Regulation of CO fixation in cyanobacteria is important both for the organism and global carbon balance. Here we show that phosphoketolase in Synechococcus elongatus PCC7942 (SeXPK) possesses a distinct ATP-sensing mechanism, where a drop in ATP level allows SeXPK to divert precursors of the RuBisCO substrate away from the Calvin-Benson-Bassham cycle. Deleting the SeXPK gene increased CO fixation particularly during light-dark transitions. In high-density cultures, the Δxpk strain showed a 60% increase in carbon fixation and unexpectedly resulted in sucrose secretion without any pathway engineering. Using cryo-EM analysis, we discovered that these functions were enabled by a unique allosteric regulatory site involving two subunits jointly binding two ATP, which constantly suppresses the activity of SeXPK until the ATP level drops. This magnesium-independent ATP allosteric site is present in many species across all three domains of life, where it may also play important regulatory functions.