Szabolcs Semsey

During the visit we made significant progress on a project comparing the effects of transcriptional regulation with translation, proteolytic and allosteric regulation. This is based on a synthetic transcription factor constructed in the Semsey lab in Copenhagen, based on the Lac repressor of E. coli, that could be controlled simultaneously by all four types of regulators. Models developed by Sandeep Krishna during this visit enabled us to explore and compare the full range of dynamical capabilities of each regulatory mechanism. A paper on this has been submitted to the Journal of Biological Chemistry. In addition, the visit triggered a new collaboration between with Aswin Seshasayee (NCBS) studying restriction-modification systems (RM-systems) in bacteria, which are thought to be important defense mechanisms against bacteriophage attack. Our preliminary simulations suggest that weak RM-systems are not particularly useful as defenses against phage, but are extremely important for creating phage that can be used by one bacterial strain as a weapon against other competing strains. A manuscript on this work is under preparation.