Singlet oxygen inhibits ATPase and proton translocation activity of the thylakoid ATP synthase CF1CFo

Singlet oxygen (1O2) produced in plants during photosynthesis has a strong damaging effect not only on both photosystems but also on the whole photosynthetic machinery. This is also applicable for the adenosine triphosphate (ATP) synthase. Here we describe the impact of 1O2 generated by the photosensitizer Rose Bengal on the ATP hydrolysis and ATP-driven proton translocation activity of CF1CFo. Both activities were reduced dramatically within 1 min of exposure. Interestingly, it is shown that oxidized thylakoid ATP synthase is more susceptible to 1O2 than CF1CFo in its reduced state, a new insight on the mechanism of 1O2 interaction with the γ subunit.