Journal: bioRxiv

Article Title: Conversion of CO2 into valuable products: Engineering the PirC-PGAM switch in cyanobacteria to direct carbon flux into desired products

doi: 10.64898/2026.02.05.703947

Figure Lengend Snippet: In Synechocystis , the PGAM-PirC switch tightly regulates the carbon flow at the branching point between upper and lower glycolysis. In this case study, the aim is to direct the carbon flow either towards lower glycolysis (succinate and isoprene excretion), by overexpressing PGAM to decrease the inhibition of PirC under nitrogen starvation (PGAM-ON state, left panel) or towards gluconeogenesis (sucrose production), by engineering a strong inhibition of PGAM by PirC (PGAM-OFF state, right panel).

Article Snippet: The pEX-K248- P petJ _pgam plasmid was synthesized by Eurofins.

Techniques: Inhibition

Journal: bioRxiv

Article Title: Conversion of CO2 into valuable products: Engineering the PirC-PGAM switch in cyanobacteria to direct carbon flux into desired products

doi: 10.64898/2026.02.05.703947

Figure Lengend Snippet: A: Plasmid design for overexpressing the native pgam gene ( slr1945 ) from the pSEVA251 plasmid under control of the moderate J23101 or strong J23119 promoter. B: Immunoblots against PGAM and PirC for cells grown under vegetative (control) conditions and for 7 days under N starvation. C-D: Vegetative growth (C) and OD 750 under nitrogen starvation (D) with at least three biological replicates. E-F: Quantification of glycogen with method A (E) and PHB (F) after 7 days of N starvation. Each dot represents a biological replicate. Dunn’s multiple comparisons test was used (ns = P > 0.05, * = P ≤ 0.05, ** = P ≤ 0.01, *** = P≤ 0.001).

Article Snippet: The pEX-K248- P petJ _pgam plasmid was synthesized by Eurofins.

Techniques: Plasmid Preparation, Control, Western Blot

Journal: bioRxiv

Article Title: Conversion of CO2 into valuable products: Engineering the PirC-PGAM switch in cyanobacteria to direct carbon flux into desired products

doi: 10.64898/2026.02.05.703947

Figure Lengend Snippet: A: Design of constructs to achieve pirC overexpression and pgam downregulation using copper controllable promoters from Synechocystis. B: Verification of recombinant strains. The obtained strains were verified by PCR, using primer combinations illustrated by grey arrows in panel A. C-E: Growth of the different mutants pgam_KD and pirC_OEX and the combination mutant of pgam_KD and pirC_OEX compared to the wildtype under inducing conditions, i.e in presence of Cu 2+ at a final concentration of 1 µM. F-H: Development of the average glycogen amount in the obtained strains compared to the WT after the addition Cu 2+ at a final concentration of 1 µM. Glycogen was measured using method B. Data are the mean ± SD of n biological replicates as indicated.

Article Snippet: The pEX-K248- P petJ _pgam plasmid was synthesized by Eurofins.

Techniques: Construct, Over Expression, Recombinant, Mutagenesis, Concentration Assay

Journal: bioRxiv

Article Title: Conversion of CO2 into valuable products: Engineering the PirC-PGAM switch in cyanobacteria to direct carbon flux into desired products

doi: 10.64898/2026.02.05.703947

Figure Lengend Snippet: For glycogen and sucrose measurements, cells were salt shocked 24 h after induction with copper ions. A: Glycogen measurement in the pgam_KD mutant before and after salt shock. B: Glycogen measurement in the pgam_KD pirC_OEX mutant before and after salt shock. Glycogen was measured using method B. Measured concentrations are shown with respect to the liquid volume of the sampled cultures at OD750. C: Sucrose content in the pgam_KD mutant at two time points before salt shock as well as 8 h after salt shock. D: Sucrose content in the pgam_KD pirC_OEX mutant at two time points before and 8 h after salt shock. Each dot represents a biological replicate. T-test was done for statistical analysis (ns = P > 0.05, * = P ≤ 0.05, ** = P ≤ 0.01, *** = P ≤ 0.001).

Article Snippet: The pEX-K248- P petJ _pgam plasmid was synthesized by Eurofins.

Techniques: Mutagenesis