Difference between revisions of "Part:BBa K3117026"

This part can form an isopeptide bond with its eqivalent SpyTag (BBa_K3117030) which was part of the project of the iGEM team 2019 FAU_Erlangen, and therefore form a bispecific antibody. The outstanding advantage of the so called SpyTag/SpyCatcher system is that you can fuse this small molecules to arbitrary structures and create a binding. This provides a basis for the establishment of large modular systems.  

The part BBa_K3117026 is a fusion protein of an anti-GPA33 single-chain variable fragment (scFv) and SpyCatcher. The sequence contains a C-terminal His-tag (BBa_K3117005) for easy purification. Secretion of the protein is ensured by an Ig leader (BBa_K3117006). When the protein passes the membrane, the leader segment is cleaved of. By connecting the variable regions of the heavy and the light chain of an anti-GPA33 antibody with a short GGGGS (BBa_K3117004) linker, the scFv retains its antigen-binding ability and is much smaller than a conventional antibody. Thus, it is well suited as part of a fusion protein with another effector. The SpyCatcher attached to the scFv belongs to the SpyTag/SpyCatcher system and is one part of the FbaB protein of Streptococcus pyogenes. Once it comes into contact with its corresponding other part, the SpyTag (BBa_K3117030), they bind covalently. This allows our part to be used in a modular manner in combination with other molecules that have the SpyTag. Since the scFv targets GPA33 which is expressed on more than 95% of colon cancers, our part is optimal for specifically directing its fusion partner (e.g. an effector protein) to colon cancer cells.