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Probing the conformational dynamics of photosystem I in unconfined and confined spaces

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Abstract

The fluorescence dynamics of Photosystem I (PSI) in bulk water and inside a confined environment like a liposome have been investigated using time resolved confocal microscopy. In bulk water, PSI exhibits a major emission peak at ∼680 nm, while in the liposome it exhibits a markedly blue shifted emission maximum at ∼485 nm. This is indicative of conformational changes due to entrapment and emergence of a stressed conformation of PSI inside the liposome. The observed time constants for the fluorescence lifetime of PSI inside the liposome are significantly high as opposed to PSI in bulk water. More interestingly, the fluorescence intensity of PSI in bulk water exhibits strong fluctuations with many high intensity jumps and these are anti-correlated with the fluorescence lifetime of PSI. In contrast, inside the liposome, no such anti-correlated behaviour is observed. We further demonstrated that PSI exhibits at least two conformational states in bulk water, whereas a single conformation is observed inside the liposome, indicating the conformational rigidity and locking of the PSI complex inside a liposome.

Graphical abstract: Probing the conformational dynamics of photosystem I in unconfined and confined spaces

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Publication details

The article was received on 31 Oct 2017, accepted on 23 Nov 2017 and first published on 23 Nov 2017


Article type: Paper
DOI: 10.1039/C7CP07375E
Citation: Phys. Chem. Chem. Phys., 2018, Advance Article
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    Probing the conformational dynamics of photosystem I in unconfined and confined spaces

    G. Das, S. Chattoraj, S. Nandi, P. Mondal, A. Saha, K. Bhattacharyya and S. Ghosh, Phys. Chem. Chem. Phys., 2018, Advance Article , DOI: 10.1039/C7CP07375E

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