Profiling of ABC transporters

PhD ceremony: Ms. J.C. Wolters, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Profiling of ABC transporters

Promotor(s): prof. B. Poolman

Faculty: Mathematics and Natural Sciences

This thesis describes a new method to enrich ATP-binding proteins, and more specifically ATP-binding cassette (ABC) transporters from complex mixtures in the cell. ABC transporters, amongst others, transport nutrients and regulate a variety of processes, like the regulation of the cell volume. The importance of the ABC transporters is shown in diseases like cystic fibrosis and drug resistance, which are caused by mutations and/or folding defects in the proteins. Next to the development of a method for the enrichment of these proteins, more detailed analyses have been performed on the osmoregulatory ABC transporter OpuA from the bacterium Lactococcus lactis. OpuA protects microorganisms from high salt concentrations (high osmolarity) in the environment. The crystal structure of the substrate-binding domain has been determined, which has yielded important information on how the receptor domain recognizes the ligand glycine betaine. Moreover, a number biophysical techniques, like electron microscopy and mass spectrometry, have been used to obtain structural information on the entire OpuA complex, which so far has been refractory to structure determination by crystallography.