Investigating transcriptional regulation of Escherichia coli PhnF - large effect of a small obstacle
PhD defence, Friday 2nd of October 2026, Rasmus Wohnsen
During his PhD studies, Rasmus Wohnsen investigated how bacteria can survive and grow using phosphonates as an alternative source of phosphorus. Phosphonates contain a strong and stable carbon–phosphorus bond that bacteria must break down to access the phosphorus. In E. coli, this process is carried out by a group of proteins encoded by the phn operon. Rasmus studied how the protein PhnF controls gene expression of these proteins and how this regulation responds to phosphonate availability. The work showed that PhnF acts as a physical roadblock to transcription from a binding site located in the middle of the phn operon, thereby preventing production of the downstream phosphonate-degrading proteins until phosphonate degradation is initiated.
This provides new insight into how the position of a regulatory protein within an operon can be used to coordinate gene expression with nutrient availability and metabolic activity.
The PhD study was completed at Molecular Biology and Genetics, Faculty of Natural Sciences, Aarhus University.
This summary was prepared by the PhD student.
Time: Friday, 2nd of October 2026, at 1 pm
Place: Building 1871, room 120, Nucleus Auditorium, Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C
Title of PhD thesis: Investigating the Molecular Mechanism of PhnF-mediated Transcriptional Regulation of the Escherichia coli phn Operon
Contact information: Rasmus Wohnsen, e-mail: rwohnsen@mbg.au.dk, tel.: +45 24 41 93 73
Members of the assessment committee:
Professor Birgitte Haahr Kallipolitis, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Denmark
Professor Yves Müller, Department of Biology, Friedrich-Alexander University of Erlangen–Nuremberg, Germany
Associate Professor Christian Kroun Damgaard (chair), Department of Molecular Biology and Genetics, Aarhus University, Denmark
Main supervisor: Professor Ditlev Egeskov Brodersen, Department of Molecular Biology and Genetics, Aarhus University, Denmark
Language: The PhD dissertation will be defended in English
The defence is public.
The PhD thesis is available for reading at the Graduate School of Natural Sciences/GSNS, Ny Munkegade 120, building 1521, 8000 Aarhus C