Targeting at the Nanoscale: A Novel S-Layer Fusion Protein Enabling Controlled Immobilization of Biotinylated Molecules.
With the aim of constructing an S-layer fusion protein that combines both excellent self-assembly and specific ligand i.e., biotin binding ability, streptavidin (aa 16-133) was fused to the S-layer protein ofSporosarcina ureaeATCC 13881 (SslA) devoid of its N-terminal 341 and C-terminal 172 amino acids. The genetically engineered chimeric protein could be successfully produced inE. coli, isolated, and purified via Ni affinity chromatography. In vitro recrystallisation experiments performed with the purified chimeric protein in solution and on a silicon wafer have demonstrated that fusion of the streptavidin domain does not interfere with the self-assembling properties of the S-layer part. The chimeric protein self-assembled into multilayers. More importantly, the streptavidin domain retained its full biotin-binding ability, a fact evidenced by experiments in which biotinylated quantum dots were coupled to the fusion protein monomers and adsorbed onto the in vitro recrystallised fusion protein template. In this way, this S-layer fusion protein can serve as a functional template for the controlled immobilization of biotinylated and biologically active molecules.
Electronics Packaging Laboratory, Department of Electrical Engineering and Information Technology, Technische Universität Dresden, Dresden 01069, Germany. varga@avt.et.tu-dresden.de.
Melinda
M
Varga
Sporosarcina ureae ATCC 13881; biotinylated molecules; quantum dots; self-assembly; surface layer protein