Quality control of peroxisome function in Penicillium chrysogenum

PhD ceremony: Ms. M.D. Bartoszewska, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Quality control of peroxisome function in Penicillium chrysogenum

Promotor(s): prof. I.J. van der Klei, prof. M. Veenhuis

Faculty: Mathematics and Natural Sciences

The research presented in the thesis of Magdalena Bartoszewska focuses on the understanding of the principles of the biology of a class of intriguing organelles termed peroxisomes, using Penicillium chrysogenum as a model organism. Peroxisomes are present in virtually all eukaryotes playing a key role in numerous anabolic and catabolic pathways, including oxidation of fatty acids, glyoxylate cycle (plants), photorespiration (plants), glycolysis (Trypanosomes), plasmalogen biosynthesis (mammals), methanol oxidation (fungi) and many others. In filamentous fungi peroxisomes also play a role in the formation of various secondary metabolites, of which some are of great biotechnological and therapeutic interest as the β-lactam antibiotic penicillin (PEN) produced by P. chrysogenum.

Organelle abundance in the cell is the resultant of both degradation and biogenic processes. Bartoszewskastudied how inhibition of the major cellular degradation pathway, termed autophagy, affects PEN production efficiency in high PEN producing P. chrysogenum strains. Her data indicate that modulation of autophagy-related processes may be a promising approach of improving β-lactam productivity in Penicillium chrysogenum.

Although peroxisomes have been described for the first time more than 40 years ago, our knowledge of the mechanisms that govern the vitality of these organelles is still in its infancy. Bartoszewska studied the function of peroxisomal lon protease (pln) in P. chrysogenum. Her data suggest that peroxisomal Lon protease constitutes an important component of protein quality control machinery in the peroxisome matrix. Sh e also analyzed the function of Pex11 family members (Pex11, Pex11B, Pex11C), as well as Pex16 and Pex3 in peroxisome biogenesis in P. chrysogenum.