Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5760197 | Journal of Theoretical Biology | 2017 | 13 Pages |
Abstract
A model was constructed which includes electron transport (linear and cyclic and Mehler type reaction) coupled to proton translocation, counter ion movement, ATP synthesis, and Calvin-Benson cycle. The focus is on modeling of the light-induced total electric potential difference (ÎΨ) which in this model originates from the bulk phase electric potential difference (ÎΨb), the localized electric potential difference (ÎΨc), as well as the surface electric potential difference (ÎΨs). The measured dual wavelength transmittance signal (ÎA515-560 nm, electrochromic shift) was used as a proxy for experimental ÎΨ. The predictions for theoretical ÎΨ vary with assumed contribution of ÎΨs, which might imply that the measured ÎA515-560 nm trace on a long time scale reflects the interplay of the ÎΨ components. Simulations also show that partitioning of proton motive force (pmf) to ÎΨb and ÎpH components is sensitive to the stoichiometric ratio of H+/ATP, energy barrier for ATP synthesis, ionic strength, buffer capacity and light intensity. Our model shows that high buffer capacity promotes the establishment of ÎΨb, while the formation of pHi minimum is not 'dissipated' but 'postponed' until it reaches the same level as that for low buffer capacity. Under physiologically optimal conditions, the output of the model shows that at steady state in light, the ÎpH component is the main contributor to pmf to drive ATP synthesis while a low ÎΨb persists energizing the membrane. Our model predicts 11 mV as the resting electric potential difference across the thylakoid membrane in dark. We suggest that the model presented in this work can be integrated as a module into a more comprehensive model of oxygenic photosynthesis.
Keywords
OATPQA, QBCOSPCytb6fΔpHCalvin-Benson cyclePSI, PSIIFNRNPQCBCGHKNADPHPFDPMFOECΔψAdenosine TriphosphateATPLETopen probabilityCyclic electron transportlinear electron transportOxygen evolving complexCETphoton flux densityElectrochromic shiftcytochrome b6fBuffer capacityPhotosynthesisFerredoxinlight harvesting complexesproton motive forcePlastocyaninplastoquinonereduced nicotinamide adenine dinucleotide phosphatesingle turnover
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Authors
Hui Lyu, DuÅ¡an Lazár,