Institute of Biochemistry, University of Muenster, Wilhelm-Klemm-Strasse 2, 48149, Münster, Germany.
International Graduate School of Chemistry (GSC-MS), University of Münster, 48149, Münster, Germany.
Chembiochem. 2019 Jan 2;20(1):72-77. doi: 10.1002/cbic.201800552. Epub 2018 Oct 30.
Semisynthetic cyclic peptides containing both non-proteinogenic building blocks, as the synthetic part, and a genetically encoded sequence amenable to DNA-based randomization hold great potential to expand the chemical space in the quest for novel bioactive peptides. Key to an efficient selection of novel binders to biomacromolecules is a robust method to link their genotype and phenotype. A novel bacterial cell surface display technology has been developed to present cyclic peptides composed of synthetic and genetically encoded fragments in their backbones. The fragments were combined by protein trans-splicing and intramolecular oxime ligation. To this end, a split intein half and an unnatural amino acid were displayed with the genetically encoded part on the surface of Escherichia coli. Addition of the synthetic fragment equipped with the split intein partner and an aminooxy moiety, as well as the application of a pH-shift protocol, resulted in the onsurface formation of the semisynthetic cyclic peptide. This approach will serve for the generation of cyclic peptide libraries suitable for selection by fluorescence-activated cell sorting, and more generally enables chemical modification of proteins on the bacterial surface.
半合成环肽既包含非蛋白原构建模块作为合成部分，又包含可进行基于 DNA 的随机化的遗传编码序列，具有极大的潜力来扩展新型生物活性肽的化学空间。有效地选择新型生物大分子结合物的关键是一种能够将其基因型和表型联系起来的稳健方法。已经开发出一种新型的细菌表面展示技术，用于展示由骨架中的合成和遗传编码片段组成的环肽。这些片段通过蛋白质转剪接和分子内肟键合组合在一起。为此，将带有遗传编码部分的分裂内含肽的一半和非天然氨基酸展示在大肠杆菌表面。添加带有分裂内含肽伴侣和氨氧基部分的合成片段，以及应用 pH 移位方案，导致半合成环肽在表面形成。这种方法将用于生成适合通过荧光激活细胞分选进行选择的环肽文库，并且更普遍地使细菌表面的蛋白质能够进行化学修饰。
