Cell surface proteins are key mediators of cell responses to changing environments. They are naturally regulated by dynamic structure, expression levels, and composition changes. Synthetic agents bearing unique functionalities can also be used to modify and control cell surface proteins. This is commonly achieved by designing biomimetics that bind natural proteins or by incorporating synthetic anchors to the cell surface, which are then chemically or enzymatically modified to acquire the desired functionality. Potential applications include detecting surface protein interactions and turning cells into living scaffolds or platforms for drug discovery. The functional entity can also be introduced via non-covalent interactions, such as protein-DNA interactions or Watson-Crick base pairing. However, versatile and straightforward techniques for synthesis and binding control are still lacking.

This technology engineers dynamic artificial receptor systems that integrate principles of both ODN-small molecule conjugates and functional synthetic agents. A hexahistidine tag (His-tag) is fused to cell surface-expressed protein, enabling its interaction with artificial nitrilotriacetic acid (NTA)-nickel (II) complex-tagged ODNs linked to a receptor or functional motif. The local concentration of synthetic receptors/functional motifs can be controlled by adding suitable chelators, which disrupt the His tag-mediated bacteria-biomimetic interaction.

Dynamic functionalization of cell surfaces is achieved by decorating cells with a His-tagged ODN (ODN-1), followed by exposure to a complementary ODN (ODN-2) bearing a functionality motif of interest. Functionality is then exchanged by sequentially incubating cells with a strand complementary to the short overhang region of ODN-2 (ODN-3), followed by the introduction of an ODN-2 bearing an alternative functional motif.

A. A schematic representation of a His-tag fused to OmpC , a protein expressed on the outer membrane of E. coli cells, linked to a X-conjugated ODN-1 through a tri-NTA group. The X-conjugated ODN-1 can be attached to any motif linked to the complementary strand, as shown in figure B. B. Dynamic alteration of the functionality demonstrated by sequentially subjecting cells to His-ODN-1, a fluorescently labeled ODN-2 (e.g., TAMRA-ODN-2), and then ODN-3 that removes the fluorescent ODN-2. The cells can then be relabeled by subjecting them to ODN-2 bearing a different fluorescent group (e.g., Cy5-ODN-2 or FAM-ODN-2). C. OmpC conjugated to a His-tag and incubated with Cy5-conjugated ODN-1. Fluorescence imaging attested to the selective labeling of bacterial cells by Cy5-ODN-1, which did not affect cell viability. Introduction of varying concentrations of EDTA, a potent nickel chelator, effectively controlled the degree of synthetic receptor coverage. From: Lahav-Mankovski et al., Nature Commun. 2020,11 :1299

This platform's extensive variability and programmability were demonstrated (published in: Lahav-Mankovski et al., Nature Commun. 2020,11 :1299). The team is currently working on tailoring this technology to cancer cell-targeting and drug screening platforms. The researcher will be willing to cooperate with other companies to integrate this technology in other specific applications.