An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria.
Nat Metab
; 5(7): 1111-1126, 2023 07.
Article
in En
| MEDLINE
| ID: mdl-37349485
ABSTRACT
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Photosynthesis
/
Carbon Dioxide
Type of study:
Diagnostic_studies
Language:
En
Journal:
Nat Metab
Year:
2023
Document type:
Article
Affiliation country:
Taiwan