Fluorescence imaging is essential to unlocking the secrets of life and has benefited greatly from the discovery of fluorescent proteins (FPs). Reversibly switchable fluorescent proteins (RSFPs, https://doi.org/10.1002/iub.1023) are capable of switching from a fluorescent 'on-state' to a non-fluorescent 'off-state' upon specific illumination, and have fostered many imaging applications, including some super-resolution methods. However, RSFPs are still imperfect: for example, their brightness is limited, their switching kinetics is dependent on environmental conditions, their resistance to irreversible photobleaching is insufficient. In particular, whereas green RSFPs are performing relatively well, red RSFPs have been lagging behind. The switching performances of green and red RSFPs are linked with their intrinsic or light-activated protein-dynamics properties and can be studied by combining structural biology approaches, such as kinetic X-ray crystallography, with optical spectroscopy and fluorescence imaging (doi: 10.1038/s41592-019-0462-3). In the proposed PhD project, those techniques will be used to better understand red RSFPs and facilitate their rational engineering towards brighter and more photo-resistant variants. The recruited student will work in close collaboration with another PhD student to be hired, who will approach the same questions by employing NMR.

Candidates should have a strong interest to work at the interface between physics, chemistry and biology. Knowledge of advanced fluorescence microscopy and/or X-ray crystallography is required. Preliminary experience in image analysis, biochemistry, cell biology and/or molecular biology will be appreciated.