Abstract
The archaeon Halobacterium salinarum can produce energy using three different processes, namely photosynthesis, oxidative phosphorylation and fermentation of arginine, and is thus a model organism in bioenergetics. Compared to its bacteriorhodopsin-driven photosynthesis, less attention has been devoted to modeling its respiratory pathway. We created a system of ordinary differential equations that models its oxidative phosphorylation. The model consists of the electron transport chain, the ATP synthase, the potassium uniport and the sodium-proton antiport. By fitting the model parameters to experimental data, we show that the model can explain data on proton motive force generation, ATP production, and the charge balancing of ions between the sodium-proton antiporter and the potassium uniport. We performed sensitivity analysis of the model parameters to determine how the model will respond to perturbations in parameter values. The model and the parameters we derived provide a resource that can be used for analytical studies of the bioenergetics of H. salinarum.
Highlights
The archaeon Halobacterium salinarum thrives in extremely salty environments using three bioenergetic processes: photosynthesis, respiration and fermentation of arginine
The mathematical model was based on the bioenergetic processes involved in oxidative phosphorylation of H. salinarum
We have shown that the respiratory pathway of H. salinarum can be modeled using a simple set of differential equations that fit experimental data from various experimental conditions
Summary
The archaeon Halobacterium salinarum thrives in extremely salty environments (around 4M) using three bioenergetic processes: photosynthesis, respiration and fermentation of arginine. When sufficient light is available, it uses bacteriorhodopsin, a membrane-bound retinal protein which drives the only known non-chlorophyll photosynthetic system, to enhance the membrane potential (ΔC) [1,2,3,4,5,6]. In the absence of light, the respiratory pathway is used by the organism to enhance the membrane potential. It can use the arginine pathway as an energy source [2, 7, 8]. Photosynthesis and respiration produce energy by enhancing the membrane potential which drives phosphorylation, while fermentation of arginine produces energy by substrate level phosphorylation. We constructed a mathematical model of its respiration to help
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