Unravelling the structure and function of the bacterial persistence regulator ObgE

The last few decades, society is facing the problem that many pathogenic bacteria are becoming insensitive to the majority of existing antibiotics. An important cause of chronic bacterial infections is the presence of persister cells, and although the clinical relevance of persistence has been proven, the mechanisms leading to this phenomenon have largely remained unresolved. Recent studies have uncovered the GTPase Obg as a central regulator of persistence in Escherichia coli and Pseudomonas aeruginosa. Thus, Obg forms a promising target for the development of anti-persister drugs. In the framework of my PhD research I set-out to structurally and functionally characterize the Obg protein from E. coli. Specifically, the first X-ray crystal structure of E. coli Obg in complex with GDP was solved and conformational changes regarding the functioning of the protein were mapped. A complete biochemical analysis of the protein provided new insights into the function of Obg and unraveled a role of its disordered C-terminal domain in nucleotide binding. In addition, the effect of in vivo identified mutants of Obg, that are affected in the persistence phenotype, on the mechanism and functioning of E. coli Obg was studied. Finally, I started investigating possible interactors that constitute the Obg persistence interactome. In particular, I have focused on the reported interaction between Obg and SpoT, a key regulator of the stringent stress response. In conclusion, these findings contribute to our understanding of the detailed molecular mechanism of Obg proteins. Therefore, our results might lead to novel insights into the role of Obg in cellular physiology, including bacterial persistence.

Publication year:2018