Remodeling of photosynthetic electron transport in Synechocystis sp. PCC 6803 for future hydrogen production from water

Kannchen, Daniela; Zabret, Jure; Oworah-Nkruma, R.; Dyczmons-Nowaczyk, Nina; Wiegand, Katrin; Löbbert, Pia; Frank, Anna; Nowaczyk, Marc M.; Rexroth, Sascha; Rögner, Matthias

doi:10.1016/j.bbabio.2020.148208

Cited by 9 publications

(9 citation statements)

References 69 publications

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“…A number of analogous fusions have been reported to increase electron transfer in the literature, including cytochrome P450 fusion to PsaM (54) or Fd (53,55), or hydrogenase fusion to PsaC (56), PsaD (57), PsaE (58), or Fd (59). Reducing the affinity of FNR (Fd-NADP + -oxidoreductase) interaction by point mutations could be used as strategy to redirect photosynthetic electrons through heterologous production pathways (60). Rationally designing engineered metabolic pathways could be used to generate heterologous sinks more responsive to dynamic conditions, analogous to natural sinks.…”

Section: Discussionmentioning

confidence: 99%

Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria

Santos-Merino

Torrado

Davis

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Cyanobacteria must prevent imbalances between absorbed light energy (source) and the metabolic capacity (sink) to utilize it to protect their photosynthetic apparatus against damage. A number of photoprotective mechanisms assist in dissipating excess absorbed energy, including respiratory terminal oxidases and flavodiiron proteins, but inherently reduce photosynthetic efficiency. Recently, it has been hypothesized that some engineered metabolic pathways may improve photosynthetic performance by correcting source/sink imbalances. In the context of this subject, we explored the interconnectivity between endogenous electron valves, and the activation of one or more heterologous metabolic sinks. We coexpressed two heterologous metabolic pathways that have been previously shown to positively impact photosynthetic activity in cyanobacteria, a sucrose production pathway (consuming ATP and reductant) and a reductant-only consuming cytochrome P450. Sucrose export was associated with improved quantum yield of phtotosystem II (PSII) and enhanced electron transport chain flux, especially at lower illumination levels, while cytochrome P450 activity led to photosynthetic enhancements primarily observed under high light. Moreover, coexpression of these two heterologous sinks showed additive impacts on photosynthesis, indicating that neither sink alone was capable of utilizing the full “overcapacity” of the electron transport chain. We find that heterologous sinks may partially compensate for the loss of photosystem I (PSI) oxidizing mechanisms even under rapid illumination changes, although this compensation is incomplete. Our results provide support for the theory that heterologous metabolism can act as a photosynthetic sink and exhibit some overlapping functionality with photoprotective mechanisms, while potentially conserving energy within useful metabolic products that might otherwise be “lost.”

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Section: Discussionmentioning

confidence: 99%

Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria

Santos-Merino

Torrado

Davis

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…A direct connection to the photosynthetic apparatus, as demonstrated for hydrogenases ( Appel et al, 2020 ; Kanygin et al, 2020 ), allowed a direct electron transfer, mitigating unwanted electron leakage. As a strategy to avoid intracellular competition for redox equivalents, FNR affinity for ferredoxin can be attenuated, thereby making more ferredoxin available for target reactions, e.g., hydrogen formation catalyzed by Fd-accepting hydrogenases ( Kannchen et al, 2020 ). The plastochinone pool in principle constitutes another attractive point to tap reducing power from photosynthesis, with native transfer to the terminal oxidase as an example ( Feilke et al, 2017 ).…”

Section: Pathway Engineeringmentioning

confidence: 99%

Exploitation of Hetero- and Phototrophic Metabolic Modules for Redox-Intensive Whole-Cell Biocatalysis

Theodosiou

Tüllinghoff

Toepel

et al. 2022

Front. Bioeng. Biotechnol.

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The successful realization of a sustainable manufacturing bioprocess and the maximization of its production potential and capacity are the main concerns of a bioprocess engineer. A main step towards this endeavor is the development of an efficient biocatalyst. Isolated enzyme(s), microbial cells, or (immobilized) formulations thereof can serve as biocatalysts. Living cells feature, beside active enzymes, metabolic modules that can be exploited to support energy-dependent and multi-step enzyme-catalyzed reactions. Metabolism can sustainably supply necessary cofactors or cosubstrates at the expense of readily available and cheap resources, rendering external addition of costly cosubstrates unnecessary. However, for the development of an efficient whole-cell biocatalyst, in depth comprehension of metabolic modules and their interconnection with cell growth, maintenance, and product formation is indispensable. In order to maximize the flux through biosynthetic reactions and pathways to an industrially relevant product and respective key performance indices (i.e., titer, yield, and productivity), existing metabolic modules can be redesigned and/or novel artificial ones established. This review focuses on whole-cell bioconversions that are coupled to heterotrophic or phototrophic metabolism and discusses metabolic engineering efforts aiming at 1) increasing regeneration and supply of redox equivalents, such as NAD(P/H), 2) blocking competing fluxes, and 3) increasing the availability of metabolites serving as (co)substrates of desired biosynthetic routes.

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“…Therefore, increasing the compatibility of the heterologous P450s with the photosystem, thus improving the electron utilizing efficiency for P450s from photosystem, would become one of the main directions of P450 photo-bioreactor improvement in the future 90 . At present, some efforts have optimized the electron transfer from photosystem I to P450 by fusion-expression of P450 and Fdx 90 , 110 , or through lowering the affinity of Fdx and FNR by point mutation of FNR to redirect the electrons to P450s 111 . We envision that more pathbreaking strategies/approaches are required and will emerge to solve this central problem associated with the algal photo-driven P450 bioreactors or cell-factories.…”

Section: Algae As Photo-bioreactors Of Heterologous P450smentioning

confidence: 99%

Cytochrome P450s in algae: Bioactive natural product biosynthesis and light-driven bioproduction

Zheng

Guo

Cheng

et al. 2022

Acta Pharmaceutica Sinica B

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Remodeling of photosynthetic electron transport in Synechocystis sp. PCC 6803 for future hydrogen production from water

Cited by 9 publications

References 69 publications

Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria

Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria

Exploitation of Hetero- and Phototrophic Metabolic Modules for Redox-Intensive Whole-Cell Biocatalysis

Cytochrome P450s in algae: Bioactive natural product biosynthesis and light-driven bioproduction

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