Regulation of Bioenergetics in Cyanobacteria

Photosynthetic bacteria known as cyanobacteria are increasingly used as sunlight-powered green cell factories for sustainable production of biofuels and value chemicals. Understanding the regulatory mechanisms of photosynthesis is essential for channelling photosynthetic energy towards desired reactions. A key aspect of photosynthetic regulation involves fine-tuning of the membrane potential that powers ATP synthesis and controls photoprotective mechanisms. This done by regulation of the ATP synthase and via ion channels and transporters on the thylakoid membrane. We strive to elucidate these mechanisms in cyanobacteria, and find ways use that new knowledge for optimisation the productivity of photosynthetic cell factories.

Background

Photosynthesis is the most important reaction on Earth. It is enabled by an electrochemical membrane potential generated by electron transport reactions in thylakoid membranes. The membrane potential, or proton motive force (pmf), drives ATP synthase to fuel carbon fixation and cell metabolism. Additionally, pmf controls photoprotective mechanisms and several other cellular processes. Precise regulation of the pmf is crucial in natural environments, and cells achieve it by adjusting the conductivity of ATP synthase to protons and by coordinated activities of thylakoid ion channels and transporters. In cyanobacteria, however, these mechanisms and channels remain largely unknown. As cyanobacteria are increasingly used as green cell factories for sustainable production of biofuels and other value chemicals, understanding the key regulatory mechanisms of cyanobacterial bioenergetics is key for channelling the energy of photosynthesis to desired reactions.

Research

We strive to understand cyanobacterial bioenergetics by identifying new ion channels in cyanobacteria and characterise their physiological roles in regulation of photosynthesis, and also try to elucidate the regulatory mechanisms of ATP synthase that allow the dynamic control of photoprotective mechanisms in fluctuating environmental conditions. We employ cutting-edge biochemical, biophysical, and imaging techniques for comprehensive analysis of photosynthetic reactions. We also investigate the possibilities of improving photosynthetic efficiency of cyanobacteria for biotechnological purposes through modulation of the pmf.

Significance

Our research will have biotechnological applications in allowing optimisation of green cell factories that utilise reducing power directly from the photosynthetic electron transfer chain. Modulation of the magnitude or composition of the pmf by targeting thylakoid ion channels and transporters presents a tool for maximising the productivity of biotechnological applications. We will identify bioenergetic bottlenecks, allowing further optimisation. Green cell factories present vast opportunities to produce desirable compounds for industrial, energy-political, and pharmaceutical purposes in a sustainable carbon-neutral manner and can play a major role in a transition towards a sustainable, circular bioeconomy. Moreover, there is great potential to increase crop productivity and climate resilience by optimising photosynthesis.