Analysis of Transferrin Conformational changes that Impact Virulence and Evolution

Structural dynamics define the transition from one protein state to another and are modulated by interactions with partners-ligands and/or chemical modifications.

They are important to control protein biological activity, govern protein evolution and their alteration can lead to diseases or death.

The long-term objective of ATRACTIVE is to understand protein structural dynamics, their regulation and how such dynamics diversify a conserved structural core to evolve in computing distinct functions.

For this, we will focus on human serum transferrin (hTF), which shares an ancient and conserved bilobed structural core composed of two domains from the type-II periplasmic binding protein domain family. This core is fundamental for maintaining iron-homeostasis in human cells conferring nutritional immunity.

The same core is harbored by proteins ubiquitous throughout the tree of life that diversified yielding transcription factors, enzymes or transport related/signaling proteins.

Bacterial pathogens to acquire iron from available sources, have evolved membrane receptors for capturing iron-loaded-hTF, transferrin binding proteins A and B (TbpA/TbpB).

This interaction is essential for the pathogenicity of many critical human pathogens, such as Neisseria sp (gonorrhoeae, meningitidis).

Our aim is to investigate the structural dynamics modulated by iron binding and release and how such are affected by the receptors in the presence or absence of drugs, following a three-pronged approach: a) Determine the structural dynamics of hTF upon iron binding in the two bilobed structures and uncover the allostery between them, b) Map the structural changes triggered by hTF-TbpA-TbpB interactions that underlie the iron release mechanism, c) Identify drugs that compromise the hTF-TbpA interaction.

To do so, cutting-edge multi-disciplinary tools will be adopted: a. smFRET, b. HDX-MS, c. Molecular-dynamic simulations, d. In vitro binding assays and ITC.