Molecular insights into evolution and mechanisms of binding, release and electron transfer between plastocyanin or cytochrome c6 and photosystem I

• Applicant: Professor Dr. Michael Hippler
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2007 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 37189714

The electron transfer reaction between plastocyanin (pc) or cytchrome c6 (cyt c6) and photosystem I (PSI) in green algae provides a unique system to gain molecular insights in general principles of protein-protein recognition. It is an attractive molecular model to investigate how electron transfer is optimized between partners in vitro and under physiological in vivo conditions where concentration of reaction partners, the pH value, the ionic strength of the solution and other parameter underlie permanent changes. We will perform site-directed mutagenesis of the plastid-encoded genes for PSI subunits PsaA/PsaB and nuclear encoded cyt c6 as well as plastid and nuclear transformation and heterologous expression of cyt c6 to alter specific residues that are important for optimal binding/ release and electron transfer between the donors and PSI. The electron transfer reaction will be analysed in vitro and in vivo by fast absorbance spectroscopy as well as chemical crosslinking techniques and mass spectrometry. It is our goal to provide indepth mechanistic understanding of how (i) binding, release and electron transfer were optimized during evolution, (ii) to provide a detailed molecular model and (iii) understand how these optimizations are reflected in the physiological performance of the alga.

• DFG Programme: Research Grants