SpyLigase peptide–peptide ligation polymerizes affibodies to enhance magnetic cancer cell capture

• DOI: 10.1073/pnas.1315776111
• Publication Date: 2014-03-18T05:41:09Z
• Authors: Jacob O. Fierer; Gianluca Veggiani; Mark Howarth
• Keywords: 0303 health sciences; Immunomagnetic Separation; Recombinant Fusion Proteins; Polymerization; 3. Good health; Ligases; 03 medical and health sciences; HEK293 Cells; Cell Line, Tumor; Neoplasms; Humans; Peptides; Protein Binding

Significance

Building proteins into assemblies faces challenges in specificity and stability of the connections. Proteins are ideally connected via peptide tags for minimal disruption of function. Streptococcus pyogenes contains a protein that locks itself together. After genetic dissection, we created a protein (SpyLigase) that locks two peptide tags together. With tags on opposite ends of an antibody or affibody (an antibody-like scaffold), SpyLigase assembled the proteins into polyantibody or polyaffibody chains. Magnetic beads can isolate specific cell types, but the small area of bead-to-cell contact means that abundant cell-specific target is required for cell capture. Polymerization of affibodies enabled capture of cancerous cells expressing less cancer marker and should enhance sensitivity of cell isolation for various research and clinical applications.