Liu Chang C, Mack Antha V, Tsao Meng-Lin, Mills Jeremy H, Lee Hyun Soo, Choe Hyeryun, Farzan Michael, Schultz Peter G, Smider Vaughn V
Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 2008 Nov 18;105(46):17688-93. doi: 10.1073/pnas.0809543105. Epub 2008 Nov 11.
We have devised a phage display system in which an expanded genetic code is available for directed evolution. This system allows selection to yield proteins containing unnatural amino acids should such sequences functionally outperform ones containing only the 20 canonical amino acids. We have optimized this system for use with several unnatural amino acids and provide a demonstration of its utility through the selection of anti-gp120 antibodies. One such phage-displayed antibody, selected from a naïve germline scFv antibody library in which six residues in V(H) CDR3 were randomized, contains sulfotyrosine and binds gp120 more effectively than a similarly displayed known sulfated antibody isolated from human serum. These experiments suggest that an expanded "synthetic" genetic code can confer a selective advantage in the directed evolution of proteins with specific properties.
我们设计了一种噬菌体展示系统，其中可利用扩展遗传密码进行定向进化。如果含有非天然氨基酸的序列在功能上优于仅含20种标准氨基酸的序列，该系统就能选择产生含有非天然氨基酸的蛋白质。我们已针对几种非天然氨基酸对该系统进行了优化，并通过筛选抗gp120抗体展示了其效用。一种这样的噬菌体展示抗体是从一个天然胚系scFv抗体文库中筛选出来的，该文库中V(H) CDR3的六个残基是随机的，它含有磺基酪氨酸，并且比从人血清中分离出的类似展示的已知硫酸化抗体更有效地结合gp120。这些实验表明，扩展的“合成”遗传密码可在具有特定特性的蛋白质的定向进化中赋予选择优势。
