Template-mediated N-to-C-terminal assembly of peptide chains and cyclic peptides on programmable heterodimeric coiled-coil scaffolds

生物体内的大多数生化过程是由酶和多蛋白复合物等蛋白质介导的。就效率和选择性而言，没有一种最先进的催化剂能与生物合成机器相竞争。蛋白质的功能是由基于底层氨基酸序列的三维结构指导的。探索序列-结构-功能关系不仅是我们了解已知蛋白质功能的基础，也是设计新的功能蛋白质和肽的基础。简单的序列-结构关系被理解为-链，α螺旋线圈，胶原蛋白三螺旋，部分锌指基序和w -结构域。然而，这些少数折叠基序涵盖了诸如控制寡聚化和结合以及蛋白质和dna识别等特性，这将允许设计简单的功能系统。本研究项目旨在利用新设计的平行异二聚螺旋结构基序作为合成肽链和环状肽的模板。合成策略是基于线圈链的关联，线圈链通过硫酯键连接到要转移的氨基酸和正在生长的肽链。基于天然化学连接的化学性质，肽链从n端延伸到c端。硫酯连接允许随后的头到尾环化，这也打算通过线圈相互作用介导。计划发展固相和固相合成方法。对于固相合成，单个反应步骤的控制是通过调整反应缓冲条件来实现的。然而，为了控制溶液中线圈介导的肽合成，需要开发一种利用正交相互作用的线圈编码。这两种合成策略将应用于环状肽库的设计和组装。该项目基于合成生物学的研究领域，旨在使用简单的构建模块来模拟复杂的生物系统。

Most biochemical processes in organisms are mediated by proteins such as enzymes and multi-protein complexes. None of the state-of-the-art catalysts can compete with the biological synthesis machineries in terms of efficiency and selectivity. Protein function is directed by the three dimensional structure which is based on the underlying amino-acid sequence. Exploring sequence-to-structure-to-function relationships is not only fundamental to our understanding of the function of known proteins but also the basis for the design of new functional proteins and peptides.Simple sequence-to-structure-relationships are understood for the beta-strand, the alpha-helical coiled coil, the collagen triple helix and in part for the zinc-finger motif and the WW-domain. However, these few folding motifs cover properties such as controlled oligomerisation and association as well as protein- and DNA-recognition, which would allow the design of simple functional systems. This research project aims to use the de novo designed parallel heterodimeric coiled-coil motif as a template in the synthesis of peptide chains and cyclic peptides. The synthesis strategy is based on the association of coil strands, which are linked to the amino acid to be transferred and to the growing peptide chain via a thioester bond. Based on the chemistry of the native chemical ligation, the peptide chain is elongated from the N-to the C-terminus. The thioester linkage allows subsequent head-to-tail cyclization, which is also intended to be mediated by coiled-coil interaction. It is planned to develop a solid-phase and a solution-phase synthesis approach. For the solid-phase synthesis, control of the individual reaction steps is achieved by tuning the reaction-buffer conditions. However, to control the coiled-coil-mediated peptide synthesis in solution, a coiled-coil code using orthogonally interacting coiled coils will be developed. Both synthesis strategies will be applied in the design and assembly of cyclic peptide libraries.The project is based in the research field of synthetic biology which aims to use simple building blocks to mimic complex biological systems.