Humboldt-Universität zu Berlin - Experimentelle Biophysik

Nicolas Liem

In late 2019, I started my PhD thesis at Hegemann lab. My research focuses on the investigation of light-activated phosphodiesterases. These enzyme rhodopsins can break down cyclic nucleotides (e.g. cGMP) depending on the illumination with light in the visible range [1]. They carry a retinal cofactor and are membrane-bound, which makes them interesting as optogenetic tools. To characterize and engineer enzyme rhodopsins, I am using electrophysiological techniques and assays with cultured cells as well as in vitro enzyme kinetic assays with membrane fractions. Eventually, my research has allowed to combine them with cyclases and cyclic nucleotide gated (CNG) channels to alter the membrane potential [2]. 

In addition to this, a multitude of physiological functions is under the control of cyclic nucleotide levels, which makes these rhodopsins interesting for a broad range of applications.

[1] Brunet, T., et al. (2019): "Light-regulated collective contractility in a multicellular choanoflagellate", Science 366(6463):326-334