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Sylvia Vitale

Anti-Fur inhibitors and Fur from Helicobacter pylori

Published on 27 November 2009


Thesis presented November 27, 2009

Abstract:
The thesis work consisted in two major axes: the study of anti-Fur peptidic inhibitors and characterization of Fur from Heli​cobacter pylori.
To struggle against multiresistant strains, new antibiotics need to be found. The Ferric Uptake Regulator Fur is a potential target. Indeed, it regulates essential functions in bacteria and is specific for prokaryotes. Four peptide aptamers (F1 to F4) able to interact with the Fur protein from Escherichia coli were previously selected in our laboratory. Peptide aptamers are combinatorial proteins and consist in a constant protein scaffold and a 13 amino acids variable loop, which is the active part, inserted within the scaffold. Linear peptides pF1 to pF4, corresponding to the variable loops of peptide aptamers F1 to F4, were tested in vitro for their ability to inhibit Fur DNA-binding activity. Several mutated and/or truncated variants were also tested. Yeast two-hybrid assays were also performed in order to study the in vivo interaction between Fur and peptides pF1 to pF4, and between aptamers F1 to F4 and Fur proteins from other pathogenic strains, such as Helicobacter pylori.
H. pylori is a strain that colonizes human gastric mucosal. The Fur protein from H. pylori was purified as a native dimer, containing one zinc per monomer. Its metal- and DNA-binding properties were studied. The cysteines bound to the zinc were identified. The crystal structure of C78S C150S double mutant was solved, in collaboration with ESRF.

Keywords:
Fur, peptide aptamer, peptide, iron, bacteria, antibacterial, DNA/protein interaction, protein/protein interaction