An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria

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

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Regulation of CO2 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 CO2 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.

Original languageEnglish
Pages (from-to)1111-1126
Number of pages16
JournalNature Metabolism
Issue number7
Publication statusPublished - Jul 2023

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Physiology (medical)
  • Cell Biology


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