On the mechanism of prokaryotic glutamate transporter homologues

PhD ceremony: Mr. M. Groeneveld, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: On the mechanism of prokaryotic glutamate transporter homologues

Promotor(s): prof. D.J. Slotboom

Faculty: Mathematics and Natural Sciences

The research summarized in the thesis of Maarten Groeneveld confirms how suitable the prokaryotic glutamate transporters are as a model system for this specific class of proteins, since they share many important characteristics with their eukaryal counterparts. In his thesis he describes research that focuses on several of these characteristics. By using the 2004 crystal structure of the Pyrococcus horikoshii protein as a basis, the differences and similarities between prokaryotic and eukaryotic glutamate transporters are investigated by him. Also he discusses the function of the trimeric organisation of these proteins in the cell membrane.

Glutamate plays an important role as a signalling molecule in the communication between nerve cells. After arrival of a signal at the end of a presynaptic cell, glutamate is released by this cell into the synapse. Receptors on a postsynaptic cell register this release of glutamate, resulting in continuation of the signal. Prolonged presence of glutamate in the synapse can lead to damage of adjacent cells and conditions of the central nervous system. To terminate the signal, transport proteins are present in the membranes of adjacent cells that ensure rapid removal of glutamate from the synapse. Glutamate transporters form a widespread family of proteins; these proteins are not only found among eukarya, but also among many prokarya (bacteria and archaea). In prokarya these proteins take up various nutrients from the environment that can act as nitrogen or carbon source. Prokaryotic transporters are often used as model proteins for their eukaryal counterparts, due to the large amount of biochemical tools that are available for prokaryotic systems.