Defence Lisanne Hameleers: "Characterizing the Unknown: Polysaccharide Utilization Loci-based Enzyme and Protein Discovery and Their Roles in Plant Cell Wall Carbohydrate Degradation"

Promotors: Prof. M.J.E.C. van der Maarel and Dr. E. Jurak

Abstract: Enzymes are incredibly versatile biological machineries that accelerate chemical reactions in all living organisms. They have vital functions for the organism’s metabolism, including the degradation of complex carbohydrates into simpler molecules to generate energy. These carbohydrates are important building blocks of all kind of biomass like plants and trees. The wide variety of carbohydrate structures present in nature is matched by a diverse group of enzymes known as Carbohydrate Active enZymes (CAZymes). Their construction plans are stored in the DNA of the organism. In some bacteria, there are specific DNA regions called Polysaccharide Utilization Loci (PULs) that help regulate the production of enzymes. These enzymes work together to detect, bind, and efficiently degrade a specific carbohydrate. However, the exact function of some enzymes are still unknown, so they are called Proteins or Domains of Unknown Function (PUFs, DUFs). This thesis explores the function of these PUFs and DUFs by conducting initial screenings on many different carbohydrates, followed by a detailed biochemical and structural characterization to unravel their roles in carbohydrate degradation. Discovering new enzymes improves our ability to predict the functions of PUFs and DUFs in genetic databases and expands our understanding of enzymes with possible applications in turning biomass into valuable products.

Dissertation