CeBiTec Colloquium
Monday, January 26th 2015, 17 c.t.
G2-104, CeBiTec Building
Prof. Dr. Jörg Nickelsen
Biozentrum der LMU München, AG Molekulare Pflanzenwissenschaften, Botanik
Biogenesis and Biomedical Utilization of Photosystem II

Cyanobacteria, algae and plants can convert light energy to chemical energy using a very similar type of photosynthetic membrane system, named thylakoids. Current molecular analyses suggest that the initial steps of the biogenesis of the cyanobacterial energy conversion system, in particular photosystem (PS) II, progress in a membrane subfraction representing a biosynthetic center which is marked by the PS II assembly factor PratA. This factor binds and delivers manganese (Mn) to PS II and, consequently, is involved in the assembly of its oxygen evolving Mn4CaO5 cluster.
Also in chloroplasts of the eukaryotic alga Chlamydomonas reinhardtii, PSII biogenesis centres – so called translation (T) zones – have been described. We have recently identified the DLA2 factor which appears to target the chloroplast psbA mRNA to these T-zones. Interestingly, DLA2 represents the E2 subunit of the plastid pyruvate dehydrogenase enzyme suggesting a crosstalk between gene expression and carbon metabolism via this protein.
In an applied approach, the oxygen evolving activity of PSII is used to provide a constant source of oxygen supply to engineered mammalian skin tissues which usually suffer from hypoxia due to poor vascularization. In particular, our data suggest that bioartificial scaffolds can be loaded with the microalgae Chlamydomonas reinhardtii, showing high biocompatibility and photosynthetic activity in vitro. When photosynthetic biomaterials were engrafted in a mouse full skin defect, the presence of the microalgae did not cause a significant native immune response in the host. Hence, the results of this study represent a first step towards the establishment of engineered autotrophic tissues and suggest that the use of photosynthetic cells can overcome a broader spectrum of hypoxic stress conditions.

Host: Prof. Dr. Olaf Kruse