Our project!

Paving the way for new diagnostic and therapeutic tools

Our aim is to develop a diagnostic technique based on artificially selected and modified peptides capable of detecting the presence of fungal pathogens in a sample collected from a patient. Briefly, our approach is as follows. Through a yeast two-hybrid assay we will select a set of peptides that show affinity towards surface proteins from different fungi (Aspergillus nidulans, A. fumigatus, Candida albicans and C. glabrata). After confirming the interaction between the surface proteins and a given peptide, we intend to attach a molecule to the peptide marker. In our project, this molecule will be a fluorescent protein, but in principle can also be an immune system activator which is then recognized by the immune cells or other chemical moiety that adds novel functionalities or increases the peptide stability.

Why peptides?

In comparison to antibodies or antibody fragments, peptides are small, easily synthesized, modified less expensively and show higher diffusion rates in tissues. We expect a diagnostic method based on small peptides to be more accurate and cheaper than other existing methods. We also expect it to have the potential for in vivo diagnosis. Furthermore, the adaptability of our approach allow other laboratories to follow it to generate and refine their own peptides with specificity towards their proteins of interest.

In this Figure an schematic representation of a Fungal Cell Wall is shown in an effort to reveal the advantage of a small PepTag vs an Antibody when both attempt to bind to a cell wall protein more exposed in the surface of this structure.
In both cases from bottom to top of the zoomed-in section, the details are as follow. The Plasma Membrane on the bottom. On top of it, the cell wall components: the β-1-3 glucan strains in light blue, chitin in purple, the β-1-6 glucan layer in grey, the glycoproteins (like Mannoproteins) as red spirals and finally both the plasma membrane proteins and the cell wall proteins can be seen in different shades of green.
Figure A illustrates an Antibody trying to bind, however the presence of the glycoproteins generate a stearic impediment for such interaction to occur. On the other hand, Figure B shows how a small peptide attached to a scaffold protein can actually pass in between the glycoproteins and bind successfully to its target cell wall protein. Upon this positive interaction, different applications result evident, in this case the binding of an Immune System Activator molecule is depicted in orange, which would result in the tagging of a specific fungal strain so as to activate the natural immune system response.