8IOE
Cryo-EM structure of cyanobacteria phosphoketolase in dodecameric assembly
Summary for 8IOE
Entry DOI | 10.2210/pdb8ioe/pdb |
EMDB information | 35617 |
Descriptor | Probable phosphoketolase, THIAMINE DIPHOSPHATE, MAGNESIUM ION (3 entities in total) |
Functional Keywords | carbon metabolism, tpp-dependent enzyme, cytosolic protein |
Biological source | Synechococcus elongatus (strain ATCC 33912 / PCC 7942 / FACHB-805) |
Total number of polymer chains | 12 |
Total formula weight | 1074993.96 |
Authors | Chang, C.-W.,Tsai, M.-D. (deposition date: 2023-03-11, release date: 2023-06-28, Last modification date: 2023-11-15) |
Primary citation | Lu, K.J.,Chang, C.W.,Wang, C.H.,Chen, F.Y.,Huang, I.Y.,Huang, P.H.,Yang, C.H.,Wu, H.Y.,Wu, W.J.,Hsu, K.C.,Ho, M.C.,Tsai, M.D.,Liao, J.C. An ATP-sensitive phosphoketolase regulates carbon fixation in cyanobacteria. Nat Metab, 5:1111-1126, 2023 Cited by PubMed Abstract: 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. PubMed: 37349485DOI: 10.1038/s42255-023-00831-w PDB entries with the same primary citation |
Experimental method | ELECTRON MICROSCOPY (2.86 Å) |
Structure validation
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