Group leader: Institute of Microbiology and Genetics, Department of General Microbiology
Major Research Interests
Glutamate is the most abundant metabolite that delivers the majority of nitrogen for synthesis of vital building blocks in any living cell. The Gram-positive bacterium Bacillus subtilis synthesizes glutamate by the combined action of the glutamine synthetase and the glutamate synthase while the glutamate dehydrogenase strictly degrades glutamate. As the glutamate synthesizing and degrading reactions form a crucial link between carbon and nitrogen metabolism, this metabolic intersection is tightly controlled. We have observed that the bacteria respond to perturbation of glutamate homoeostasis by the rapid accumulation of suppressor mutations. The specific and fast activation and inactivation of genes involved in glutamate metabolism strongly resembles the Lamarckian mode of evolution. We want to address the question how the bacteria sense the need to change their genetic make-up to maintain glutamate homoeostasis.
We are also interested in the control of the transcription factor PrfA in Listeria monocytogenes. L. monocytogenes is a Gram-positive bacterium that lives usually in the soil. However, ingested by contaminated food, the bacterium may cause gastroenteritis and abortions in pregnant women with a high mortality rate. Upon ingestion of the bacteria by humans the transcription factor PrfA directly activates the expression of about 10 genes encoding the major virulence factors. There is strong indication that signals derived from carbon metabolism are involved in the process. Thus, the carbon source provides a cue for the control of PrfA activity. However, the underlying molecular mechanism is yet unclear. We want to find an answer to the long-standing open question how PrfA activity is regulated by the available carbon source.
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