SORS: Constraints and variability of complementarity determining regions in antibodies

Date: Thursday, 10 May, 2018 – 15:00

Speakers: Alba Lepore, postdoctoral researcher at the Biozentrum University of Basel & SIB Swiss Institute of Bioinformatics.

Venue: Aula de Teleensenyament

Abstract: Antibodies have been very extensively investigated for decades and therefore much is known about their sequence-structure-function relationship. The ability of accurately modeling the structure of antibodies stems from the recognition that the hypervariable loops only exhibit a limited number of main-chain conformations called “canonical structures”. Most sequence variations in five of these loops only modify the surface generated by the side chains on a canonical main chain structure. The third loop of the heavy chain (H3) has a different behavior, and has revealed to be very difficult to model given its high variability in both length and structure. We applied a machine-learning approach combining sequence and structural related features to identify candidate loops as templates to build the structure of a target H3 loop. Models are subsequently ranked based on a score reflecting the likelihood of the presence/absence of specific interactions between the H3 residues and its structural environment. The method has led to a significant improvement in the prediction of the H3 region and the overall antigen-binding site.