Research objectives and content
Membranes of the thermoacidophilic archaeon Sulfolobus solfataricus contain membrane-spanning bipolar tetraether lipids, which contribute to the thermostability of this organism. Liposomes have been constructed from these isolated lipids and membrane proteins originating from mesophilic organisms have been functionally reconstituted in these liposomes. These proteoliposomes constitute an excellent model system for the study of transport proteins of S. solfataricus in their natural environment. In this Ph.D. project a secondary transport system of S.solfataricus will be functionally and structurally characterised. At present information about the genes of transport systems of S solfataricus is available. The first gene encoding for a putative secondary transport protein has been identified upstream of the lac S gene, which codes for B-galactosidase activity. This gene and two others published recently in the framework of the genome sequencing project of S. solfataricus has already been cloned in Escherichia coli. These genes will be (over)expressed in E. coli or in the yeast Schizosaccharomyces pombe. His-tagged proteins will be genetically constructed which will facilitate the isolation of the proteins after heterologous expression. The isolated transporters will be reconstituted into liposomes of tetraether lipids. These proteoliposomes will be used as model system to study in detail the functional properties of one of these proteins such as the substrate specificity, thermostability and energetics. Training content (objective, benefit and expected impact)
This will be the first detailed study of a specific transport system of an extreme thermoacidophilic archaeon at the biochemical, biophysical and molecular biological level. During these studies in the host laboratory extensive knowledge will be obtained about structural and functional properties of membranes of these archaea and also of other micro-organisms. The host laboratory is the ideal place to obtain this knowledge since it has a long standing and internationally acknowledged experience in the field of transport studies and bio-energetics.
Links with industry / industrial relevance (22)
Membrane proteins and the membrane lipids from S. solfataricus are highly thermostable. Liposomes and proteoliposomes derived from proteins and lipids of these organism are currently studied for application in biosensors and for matrices for macromolecules on monolayers.