Department of Molecular Genetics, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
ACS Synth Biol. 2022 Sep 16;11(9):3078-3087. doi: 10.1021/acssynbio.2c00343. Epub 2022 Sep 5.
Mersacidin is an antimicrobial class II lanthipeptide. Lanthipeptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs), characterized by intramolecular lanthionine rings. These rings give lanthipeptides their bioactive structure and stability. RiPPs are produced from a gene cluster that encodes a precursor peptide and its dedicated unique modification enzymes. The field of RiPP engineering aims to recombine modification enzymes from different RiPPs to modify new substrates, resulting in new-to-nature molecules with novel or improved functionality. The enzyme MrsM from the mersacidin gene cluster installs the four lanthionine rings of mersacidin, including the uniquely small ring A. By applying MrsM in RiPP engineering, this ring could be installed in linear peptides to achieve stabilization by a very small lanthionine or to create small lanthionine-stabilized modules for chemical modification. However, the formation of unique intramolecular structures like that of mersacidin's ring A can be very stringent. Here, the formation of ring A of mersacidin is characterized by mutagenesis. A range of truncated mersacidin variants was made to identify the smallest possible construct in which this ring could still be formed. Additionally, mutants were created to study the flexibility of ring A formation. It was found that although the formation of ring A is stringent, it can be formed in a core peptide as small as five amino acids. The truncated mersacidin core peptide CTFAL is the smallest ribosomally produced lanthipeptide reported to date, and it has exciting prospects as a new module for application in RiPP engineering.
美拉菌素是一种抗菌的 II 类短杆菌肽。短杆菌肽是一类核糖体合成和翻译后修饰的肽（RiPPs），其特征是分子内的硫醚键环。这些环赋予短杆菌肽生物活性结构和稳定性。RiPPs 是由基因簇产生的，该基因簇编码前体肽及其专用的独特修饰酶。RiPP 工程领域旨在重组来自不同 RiPP 的修饰酶来修饰新的底物，从而产生具有新颖或改进功能的新天然分子。来自美拉菌素基因簇的 MrsM 酶安装美拉菌素的四个硫醚键环，包括独特的小环 A。通过在 RiPP 工程中应用 MrsM，该环可以安装在线性肽中，通过非常小的硫醚键实现稳定，或者为化学修饰创建小的硫醚键稳定模块。然而，像美拉菌素的环 A 那样的独特分子内结构的形成可能非常严格。在这里，通过突变来表征美拉菌素环 A 的形成。制作了一系列截断的美拉菌素变体，以确定仍然可以形成该环的最小可能构建体。此外，还创建了突变体来研究环 A 形成的灵活性。结果发现，尽管环 A 的形成很严格，但它可以在小至五个氨基酸的核心肽中形成。截断的美拉菌素核心肽 CTFAL 是迄今为止报道的最小核糖体产生的短杆菌肽，它作为 RiPP 工程应用的新模块具有令人兴奋的前景。
