Sortase-click strategy for defined protein conjugation on a heptavalent cyclodextrin scaffold

: Multivalent proteins or protein dendrimers are useful for clinical and biotechnological applications. However, assembly of chemically defined protein dendrimers is a challenging endeavor. In the past, majority of protein dendrimers have been developed on branched lysine scaffolds and are usually limited to a valency of two to four. The naturally occurring cyclodextrin (CD) scaffold composed of 6-8 glucose units offers the possibility of expanding the valency. Here we have adapted a chemoenzymatic-click strategy for displaying heptavalent peptides and large proteins on the β-cyclodextrin (β-CD) scaffold. We demonstrate that recombinant proteins (engineered with a LPXTG pentapeptide motif at the carboxy terminus), labeled with an alkyne moiety by sortase-mediated ligation, can be easily clicked on to the azide-derivatized β-cyclodextrin through the Huisgen cycloaddition reaction yielding a well-defined heptavalent display of proteins.