Immobilization of bacteriophage Qbeta on metal-derivatized surfaces via polyvalent display of hexahistidine tags.

Metal-binding peptide motifs are widely used for protein purification, catalysis, and metal-mediated self assembly in the construction of novel materials and multivalent light harvesting complexes. Herein we describe hexahistidine sequences incorporated into the virus-like particle derived from bacteriophage Qbeta via co-expression of the wild-type (WT) and hexahistidine-modified coat proteins in Escherichia coli. The resulting polyvalent display of approximately 37 hexahistidine moieties per virion gave rise to altered properties of Zeta potential and hydrodynamic radius, but no observed change in stability compared to WT. While the resulting display density did not permit hexahistidine chains to cooperate in the coordination of heme, the multiple tags did impart a strong affinity for immobilized metal ions. A dissociation constant for binding to Ni-NTA of approximately 10nM was measured by SPR under non-competitive, physiological conditions. Affinity chromatography over immobilized metal columns was used to purify the particles from both crude cell lysates and after chemical derivatization. These results illustrate the potential of metal-NTA surfaces for the self-assembled presentation of multi-functionalized particles to interrogate systems ranging from small molecule binding to whole cell interactions.