Biological systems exhibit sophisticated responses to environmental and chemical perturbations, often involving fast (microsecond) conformational dynamics of their protein building blocks. These dynamics are difficult to resolve in ensemble measurements, which average over all conformations and all dynamical processes. Single-molecule spectroscopy overcomes this limitation by monitoring individual proteins, yet has been generally limited to hundreds of milliseconds or seconds timescales because of the small signals produced by a single molecule. Here, we describe extension and application to single-molecule data of an analysis method based on the correlation function of the fluorescence lifetime. We use this approach to study photoprotective quenching in oxygenic photosynthesis. Through this study, we identify the chlorophyll and carotenoids likely responsible for quenching, gaining a mechanistic understanding of how photosynthetic systems respond to sunny conditions.

Single-molecule correlation spectroscopy reveals rapid conformational dynamics in photosynthetic proteins

2019 Spring National Meeting

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