Abstract

From a structural point of view, phytochrome mediated light signaling in plants and bacteria constitutes a scarcely understood system. Albeit the tremendous research activity in the field, no X-ray or NMR-based structural information is available. For the first time now, the crystal structures of two cyanobacterial response regulators (RR), which directly interact with bacterial phytochrome receptors, have been solved. This could be accomplished by heterologous expression, purification and crystallization of the proteins, and X-ray structure determination, employing multiple anomalous wavelength dispersion (MAD) and molecular replacement (MR) techniques.