利用S-层蛋白在苏云金芽胞杆菌细胞表面展示多聚组氨酸肽

S-层(S-layer)是由单一的蛋白或糖蛋白组成的薄层晶状结构,它广泛存在于古细菌和真细菌细胞的最外表面,可包裹整个细胞。S-层在结构化学、形态学、遗传学以及物理化学等方面具有独特的性质,使之在生物技术、分子纳米技术和仿生学等领域蕴藏着广泛的应用潜力。近年来,随着微生物表面展示技术的兴起和展示系统的逐渐成熟,继外膜蛋白、附屑结构蛋白、粘附蛋白以及凝集素等表面蛋白之后,S-层蛋白被作为一种新的表面展示载体成功的在细胞表面展示了一些外源大分子。多聚组氨酸肽是由若干个单位的六聚组氨酸串联而成的短肽。六聚组氨酸能够有效的吸附镍、镉等重金

DISPLAYING POLYHISTIDINE PEPTIDE ON THE CELL SURFACE OF BACILLUS THURINGIENSIS BY S-LAYER PROTEIN

Cell surface layer (S-layer) is the outmost structure of bacterium cell and covers the intact cell. S-layer protein of Bacillus thuringiensis strain CTC (CTC protein) was used as carrier protein to display polyhistidine (polyHis) peptides on the cell surface. Series fusion protein genes were constructed by inserting DNA fragments encoding (6His)1, (6His)2, (6His)3, (6His)9 and (6His)15 polyHis peptides into CTC protein gene at the site of downstream of slh domain. With the help of re-combinant plasmid pBMB-CSA, which contains operon csaAB needed for S-layer protein anchoring on cell surface, fusion protein genes were expressed in crystal negative B. thuringiensis strain 4Q7. SDS-PAGE profiles demonstrated that all the fusion proteins except CTC-(6His)15 were expressed. Ni-NTA-agarose beads binding test showed that all recombinant strains could attach to agarose beads except 4Q7 (pBMB-CSA, pBMB-SH15). Cd2+ adsorption test indicated that the adsorption ability of all recombinant strains except 4Q7 (pBMB-CSA, pBMB-SH15) were higher than that of host strains. The Cd2+ adsorption quantity of the recombinant strain with strongest adsorption ability was twice higher than that of host strain.