How do glycolytic routes and especially the newly discovered Entner-Doudoroff pathway contribute to the central carbon metabolism in cyanobacteria and do they play an essential role for carbon fixation and photosynthesis?
Final Report Abstract
The Calvin-Benson-Bassham (CBB) cycle is a self-sustaining cycle for the fixation of CO2. Our data show that glycolytic shunts support the regeneration of the cycle under dynamic light conditions. Glycolytic shunts are especially of importance for the activation of the CBB cycle after incubation in darkness and utilize internal glycogen reservoirs of the cell. Catabolic (glycolytic shunts) and anabolic (CBB cycle) processes thus interact for finetuning and stress the importance of bidirectionalty in metabolism. Four patterns of labeled glucose (1-13C, 3-13C, 6-13C, U-13C) were successfully utilized to determine glycolytic fluxes in Synechocystis under photomixotrophic conditions. These analyses show, that the ED pathway is, in contrast to our expectations, neglectable under metabolic steady-state conditions. The same holds true for the phosphoketolase pathway. Glucose is fed via Pgi and OPP shunt into the CBB cycle under these conditions. The clarification of the significance of the ED pathway in Synechocystis requires further investigations, as flux analyses on the one hand and the phenotype of the eda deletion mutant on the other hand, yield partly contradictory results. The enzyme Eda might e.g. possess regulatory moonlightning functions or catalyze additional reactions. Collectively, our data show, that Eda is neglectable under metabolic steady-state, whereas it is of importance under dynamic conditions.
Publications
- (2018) Hypothesis on the Synchronistic Evolution of Autotrophy and Heterotrophy. Trends in Biochemical Sciences 43: 402-411
Gutekunst, K.
(See online at https://doi.org/10.1016/j.tibs.2018.03.008) - (2019): PHB is Produced from Glycogen Turn-over during Nitrogen Starvation in Synechocystis sp. PCC 6803. International Journal of Molecular Sciences 20: 1942
Koch, M., Doello, S., Gutekunst, K., Forchhammer, K.
(See online at https://doi.org/10.3390/ijms20081942) - In vivo Fusion der Hydrogenase an Photosystem. Patent (2.12.2019) CAU047_PAT1738DE-1
Jens Appel, Kirstin Gutekunst
- (2020) Cyanobacterial in vivo solar hydrogen production my means of a photosystem I-hydrogenase (psaDhoxYH) fusion complex. Nature Energy
Appel, J., Hueren, V., Boehm, M., Gutekunst, K.
(See online at https://doi.org/10.1038/s41560-020-0609-6) - (2020) Glycolytic shunts replenish the Calvin-Benson-Bassham cycle as anaplerotic reactions in Cyanobacteria. Molecular Plant 13: 471-482
Makowka, A., Nichelmann, L., Schulze, D., Spengler, K., Wittmann, C.,Forchhammer, K., Gutekunst, K.
(See online at https://doi.org/10.1016/j.molp.2020.02.002) - (2020) In-vivo quantification of electron flow through photosystem I – Cyclic electron transport makes up about 35% in a cyanobacterium Biochimica et Biophysica Acta (BBA) – Bioenergetics
Theune, M. L., Hildebrandt, S., Steffen-Heins, A., Bilger, W., Gutekunst, K., Appel, J.
(See online at https://doi.org/10.1016/j.bbabio.2020.148353) - (2020) The structure and reactivity of the HoxEFU complex from the cyanobacterium Synechocystis sp. PCC 6803. Journal of Biological Chemistry 295: 9445-9454
Arzt, J.H., Tokmina-Lukaszewska, M., Mulder, D.W., Lubner, C.E., Gutekunst, K., Appel, J., Bothner, B., Boehm, M., King, P.W.
(See online at https://doi.org/10.1074/jbc.ra120.013136)
