Principal Investigator Shuguang Zhang
Co-investigator Rui Qing
S-layer proteins of various lattice-forming types are the most abundant protein by mass on earth. They form the outermost cell crystalline component in a broad range of bacteria and archaea in nature. They are porous monomolecular layer with crystalline unit cell size in tens of nanometers. These monomer proteins are capable of forming self-assembled mono- or double layers. After isolate them from the cell surface or through recombinant protein production, they are able to form very ordered 2D crystal lattice on a variety of non-cellular surfaces, including hydrophobic, hydrophilic, non-conducting, semi-conducting and conducting surfaces. We studies S-layer SbpA protein, found in mesophilic organism Lysinibacillus sphaericus, which completely cover the cell surface with square lattice crystallinity. Wild type SbpA (wtSbpA) proteins have been studied extensively. The recombinant SbpA (rSbpA) can be genetically modified and expressed in E.coli in different truncated forms. Previous studies showed that rSbpA is capable of forming the ordered lattice structure on some surfaces. Using both the purified wt-SpbA and truncated rSbpA proteins, we reproduced the unique two-dimensional self-assembly pattern on silicon wafer and other solid surfaces of electronic devices interests. By surface modification and changing recrystallization buffer environment, we can promote or regulate the self-assembly of SbpA on substrates. This enables a potential means of creating complex functional nanostructure. Delicate control of the self-assembly processes of S-layer on surfaces also serves the prerequisite of building the supramolecular structure as bio-electronic platform through protein fusing and anchoring on surface. Scale-up production and understanding the detailed interaction of the S-layer interface will benefits the general progress of nanobiotechnology and synthetic biology.