Crystallization
Our group investigates structure-function relationships of Channelrhodopsins (ChR). Our understanding of these proteins is currently limited by a lack of knowledge about structural rearrangements during gating and transport of the ions across the membrane. Crystallization of integral membrane proteins in general continues to be a challenge. These proteins are difficult to express, they are highly hydrophobic and therefore require detergent micelles to be stabilized in solution. This makes them significantly less likely to crystallize than soluble proteins. Our research focuses on the production of stable proteins for structural studies. Various ChRs from different algae are heterologously expressed in established cell culture systems to gain high quality material. To produce highly diffracting crystals we continuously optimize cell culture conditions, protein purification and crystallization techniques. This also includes procedures that stabilize the proteins prior and during the crystallization and that prevent inhomogeneities. Our main goal is to explore structural dynamics of the proteins by comparing the open and closed states of the channel. Moreover, functional analysis of specific proteins is performed in our laboratory.