Structural basis of signal transduction in archaeal phototaxis

• Applicants: Professor Dr. Valentin Gordeliy; Dr. Johann P. Klare
• Subject Area: Structural Biology ; Biophysics
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 430170559

The goal of the project is to elucidate the structural basis of signal transduction in archaeal phototaxis by determining the molecular mechanism of transmembrane and cytoplasmic signal transfer in the photoreceptor Natronomonas pharaonis sensory rhodopsin II with its cognate signal transducer Htr (NpSRII/NpHtrII) which is an excellent model system for studying two component systems (TCS). Membrane-embedded sensors are the key components for each organism’s communication with the outside world, and TCS are the most abundant sensing systems used by bacteria, archaea and plants. In particular, TCS is utilized extensively by pathogenic microorganisms for survival in hosts and for overcoming virulence. Thus, elucidation of the TCS signaling mechanism would help to develop novel antimicrobials.The laboratories participating in this project have vast expertise in working with two component systems, in particular with the sensory rhodopsin-transducer complex, and membrane proteins in general. The participating groups have unique and complementary skills in tackling of structural biology problems. They have demonstrated efficiency in common projects on TCS sensors. The Gordeliy laboratory has long-standing experience in membrane protein production, crystallization and structure determination. The Klare laboratory also has experience in (mutant) membrane protein production and site-directed labeling (for in vitro and in vivo applications) in combination with computational approaches to elucidate the structure, conformational dynamics and functional properties of proteins and protein complexes. Finally, the MIPT laboratory is a recently established group led by Dr. Ivan Gushchin, a young research group leader, who has extensive experience in structural biology projects, including crystallization and structure determination of membrane proteins as well as computational techniques.The project is focused on determination of the structure of protein complex NpSRII/NpHtrII and its fragments. The obtained structures will shed light on the atomic details of signal transduction. In addition to X-ray diffraction and Cryo-EM experiments, small angle scattering experiments are expected to highlight the large-scale conformational changes and guide modeling efforts. All of the obtained structural models will then be tested by a mutational approach in order to analyze the physiological properties of the proteins by applying for example photocycle- or time resolved EPR-measurements.Important preliminary work for the project has already been performed and it reveals the feasibility of the proposed experiments. The project will result in significant advances in answering fundamental questions of structural biology such as protein/protein interaction in membranes, transmembrane signal transfer, allosteric signaling, and signal amplification. Finally, these investigations might contribute to development of new antibiotics.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research, until 3/2022
• Cooperation Partner: Dr. Ivan Gushchin, until 3/2022