Periodic Reporting for period 2 - FCSSSLP (First Chemoselective Synthesis and Structural Studies of Lasso Peptides)
Reporting period: 2018-07-05 to 2019-07-04
The advantages in using peptides as drugs are their high specificity coupled to a large biological activity. They present a great diversity as therapeutic targets (antibiotics/antifungals, antivirals, cancer, etc). However, several difficulties have prevented them from being widely used as drugs. Peptides show low metabolic stability, they are rapidly degraded in vivo by proteases and the most common form of administration is intravenously, which highly prevent its degradation. In principle, these problems should be minimized with lasso-peptides. The rigidity and high packing (lasso-type) endow them with enormous stability against proteolytic degradation, physical/chemical denaturants. The first years of the project, at TSRI and under the guidance of Prof. Baran, we focused on exploring different synthetic methodologies with the final aim of preparing lasso peptides to study their recognition features and eventually their applications as putative drugs.
In the last year of the project, carried out at the Center for Cooperative Research in Biosciences (CIC bioGUNE) under the guidance of Professor Jimenez-Barbero, we focused on the study of protein-ligand molecular recognition processes of biomedical interest. In particular, I was trained in the applications of state-of-the-art Nuclear Magnetic Resonance (NMR) techniques and computational methods in this area.
Since the target Microcin J25 lasso peptide was elusive and could not be prepared either by organic or enzymatic synthesis, maintaining the essence of the DoA work-packages, we focused on the molecular recognition study of a biologically highly relevant system: the Heparan Sulfate/FGFR Ig2 system, of interest in cancer and inflammation.
All the studies carried out during these last months have been done following the same strategy described in the DoA to keep my training objectives. Thus, I performed the overexpression of the FGFR-Ig2 growth factor following molecular biology methods, the structural elucidation of a biomacromolecule: Heparan Sulfate octasaccharide (13C/15N double labelled), and learnt molecular dynamics simulations protocols and applied them to this interacting system. MD simulations were carried out using AMBER, while docking methods used AutoDock. The NMR data were assisted by the computational protocols to obtain a detailed interaction 3D model, which is displayed below.