Photosynthesis of ATP—Electrons, Proton Pumps, Rotors, and Poise

@article{Allen2002PhotosynthesisOA,
  title={Photosynthesis of ATP—Electrons, Proton Pumps, Rotors, and Poise},
  author={John F. Allen},
  journal={Cell},
  year={2002},
  volume={110},
  pages={273-276}
}
Light-driven electron transport is coupled to ATP synthesis in chloroplasts. While the nature of the coupling and the structures of key components are now known, there has long been disagreement over pathways of electron transport. Recent results now put an old idea back on the agenda-cyclic electron transport around photosystem I. 
Cyclic electron transport around photosystem I: genetic approaches.
  • T. Shikanai
  • Biology, Medicine
  • Annual review of plant biology
  • 2007
TLDR
It is necessary to reconsider the fundamental mechanisms of chloroplast energetics and clarify the essential functions of this electron flow in both photoprotection and photosynthesis. Expand
Plants Increase Photosynthesis Efficiency by Lowering the Proton Gradient across the Thylakoid Membrane
In chloroplasts, the pigments of the light-harvesting complex channel light energy to PSII and PSI. The light energy is used to separate an electron from PSII, starting its cascade through theExpand
Integrating the proton circuit into photosynthesis: progress and challenges
The formation of trans-thylakoid proton motive force (pmf) is coupled to light-driven electron transfer and both powers the synthesis of ATP and acts as a signal for initiating antenna regulation.Expand
Dynamic flexibility in the light reactions of photosynthesis governed by both electron and proton transfer reactions.
TLDR
It is argued that chloroplasts need two types of flexible mechanisms: one for modulating the output ratio of ATP:NADPH, which involves cyclic electron flux around photosystem I; and another for changing the regulatory sensitivity of the light-harvesting antenna to electron (and proton) flow. Expand
Regulating the proton budget of higher plant photosynthesis.
TLDR
In vivo probes of the proton circuit in wild-type and a mutant strain of Arabidopsis thaliana show that regulation of light capture is modulated primarily by altering the resistance of proton efflux from the thylakoid lumen, whereas modulation of propton influx through cyclic electron flow around photosystem I is suggested to play a role in regulating the ATP/NADPH output ratio of the light reactions. Expand
The regulation of the chloroplast proton motive force plays a key role for photosynthesis in fluctuating light.
TLDR
The acidification of the lumen, as an intermediate product of photosynthesis, plays an important role by regulating photosynthesis in response to excitation energy levels. Expand
Regulatory network of proton motive force: contribution of cyclic electron transport around photosystem I
  • T. Shikanai
  • Chemistry, Medicine
  • Photosynthesis Research
  • 2016
TLDR
This mechanism sacrifices homeostasis of the thylakoid lumen pH, seriously disturbing the pH-dependent regulation of photosynthetic electron transport, induction of qE, and downregulation of the cytochrome b6f complex. Expand
Cyclic electron flow around photosystem I is essential for photosynthesis
TLDR
Evidence that cyclic flow is essential for efficient photosynthesis is presented, by constructing mutants in Arabidopsis thaliana in which both PSI cyclic pathways are impaired, and present evidence that linear flow from water to NADP+ is commonly used. Expand
Contribution of Cyclic and Pseudo-cyclic Electron Transport to the Formation of Proton Motive Force in Chloroplasts.
TLDR
To avoid damage to photosynthetic electron transport by periods of excess solar energy, plants employ an intricate regulatory network involving alternative electron transport pathways, ion transporters/channels, and pH-dependent mechanisms for downregulating photosynthetics electron transport. Expand
Functions of REP27 and the low molecular weight proteins PsbX and PsbW in repair and assembly of photosystem II
Oxygenic photosynthesis is the major producer of both oxygen and organic compounds on earth and takes place in plants, green algae and cyanobacteria. The thylakoid membranes are the site of the ...
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 21 REFERENCES
THE CHLOROPLAST ATP SYNTHASE: A Rotary Enzyme?
TLDR
A critical evaluation of the evidence in support of and against the notion that one part of the enzyme rotates with respect to other parts during catalytic turnover concludes that although rotation can occur, whether it is required for activity of the ATP synthase has not been established unequivocally. Expand
Structural biology: Proton-powered turbine of a plant motor
TLDR
This work has imaged the ATP synthase from leaf chloroplasts by using atomic force microscopy and, surprisingly, finds that its turbine has 14 subunits, arranged in a cylindrical ring. Expand
Concerning a dual function of coupled cyclic electron transport in leaves.
TLDR
Coupled cyclic electron transport is assigned a role in the protection of leaves against photoinhibition in addition to its role in ATP synthesis and avoidance of overreduction of the electron transport chain is a prerequisite for the efficient protection of the photosynthetic apparatus against photo inactivation. Expand
Molecular mechanisms of photosynthesis
TLDR
This chapter discusses the organization and structure of Photosynthetic Systems, as well as the history and development of Photosynthesis, and the origins and evolution of photosynthesis. Expand
Photosynthetic control of chloroplast gene expression
TLDR
Here it is shown that the redox state of plastoquinone also controls the rate of transcription of genes encoding reaction-centre apoproteins of photosystem I and photosystem II, and the stoichiometry between the two photosystems changes in a way that counteracts the inefficiency produced when either photosystem limits the rates of the other. Expand
Photosynthesis by Isolated Chloroplasts
TLDR
Evidence is given for the action of the photochemically generated assimilatory power on two phases of the reductive carbohydrate cycle in isolated chloroplasts: the carboxylative phase which includes the phosphorylation of ribulose monophosphate and the fixation of COZ, and the reduction of 3-phosphoglyceric acid and the formation of hexose phosphate. Expand
PGR5 Is Involved in Cyclic Electron Flow around Photosystem I and Is Essential for Photoprotection in Arabidopsis
TLDR
It is proposed that the PGR5 pathway contributes to the generation of a Delta(pH) that induces thermal dissipation when Calvin cycle activity is reduced, thus preventing photosystem I photoinhibition. Expand
A quantitative model of the domain structure of the photosynthetic membrane.
A model is presented that gives a quantitative picture of the distribution of the photosynthetic components in the photosynthetic membrane of higher plants. A salient feature of the model is thatExpand
Involvement of state transitions in the switch between linear and cyclic electron flow in Chlamydomonas reinhardtii
TLDR
The results demonstrate that the transition from state 1 to state 2 induces a switch from linear to cyclic electron flow in this alga and reveal a strict cause–effect relationship between the redistribution of antenna complexes during state transitions and the onset of cyclic electrons flow. Expand
Molecular recognition in thylakoid structure and function.
TLDR
This work describes a model for the chloroplast thylakoid membrane that is consistent with recent structural data that specify the relative dimensions of intrinsic protein complexes and their dispositions within the membrane. Expand
...
1
2
3
...