Congeneric Lantibiotics from Ribosomal In Vivo Peptide Synthesis with Noncanonical Amino Acids
Congeneric Lantibiotics from Ribosomal In Vivo Peptide Synthesis with Noncanonical Amino Acids
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DOI：
10.1002/anie.201106154
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Suessmuth, Roderich D.
中科院分区：
文献类型：
--
作者：
Oldach, Florian;Al Toma, Rashed;Suessmuth, Roderich D.
核糖体合成的肽类抗生素是细菌和真菌合成的一类重要的次级代谢产物。其中包括羊毛硫抗生素，由各种革兰氏阳性细菌产生的含羊毛硫醚（Lan）的生物活性多环肽抗生素。羊毛硫抗生素表现出抗多种病原菌（例如金黄色葡萄球菌）的抗微生物活性。[1]在核糖体肽合成（RPS）之后，肽被后修饰。在羊毛硫抗生素的情况下，氨基酸Ser/Cys和Thr/Cys分别形成含硫醚的氨基酸Lan和MeLan（方案1）。[2]试图扩大这种肽的结构多样性受到限制的限制核糖体肽合成（RPS）的一组20个典型的氨基酸（cAA）。虽然这些肽的全合成方法的可行性虽然巧妙，但有限，[3]仅利用容易获得的官能团的半合成修饰已被开发，并且定点诱变方法也取得了有限的成功。[4]表达蛋白连接（EPL）允许产生具有几乎无限数量的非典型氨基酸（ncAA）的半合成蛋白。[5]尽管可以克服ncAA仅递送至靶蛋白的肽部分的固有限制，如Benkovic和Schultz最近所示，[6]但该方法的产物产率极低。相比之下，氨基酸的残基特异性替换[7]通常不会存在此类缺点，是通过直接将各种ncAA翻译成生物活性肽来实现有效化学多样化的更有前途的策略。最近，已经报道了在无细胞翻译系统（体外）中形成羊毛硫醚的可能性，[8]而我们和其他人成功地在革兰氏阴性大肠杆菌中通过RPS作为异源宿主表达了羊毛硫醚抗生素。[9，10]这种细菌宿主是迄今为止遗传密码工程最有效的平台，通过该平台，一种或多种类型的ncAA被协同掺入靶多肽序列中。[11]因此，应该可以将重组表达用于方案1。通过扩展氨基酸库设计核糖体肽抗生素的合成可能性的扩展。羊毛硫抗生素的重编程体内合成包括三个水平的化学多样化：1）共翻译，通过插入各种ncAA，包括一些具有独特化学柄的ncAA，2）翻译后，即特征羊毛硫氨酸的酶促加工和组装（Lan，MeLan），和3）生物合成后，使得能够在生理条件下通过生物正交缀合来定制羊毛硫抗生素的结构（例如通过点击化学连接各种配体，例如发色团和药效团）。
Ribosomally synthesized peptide antibiotics constitute an important group of secondary metabolites synthesized by bacteria and fungi. Among these are lantibiotics, lanthionine (Lan)-containing bioactive polycyclic peptide antibiotics produced by various Gram-positive bacteria. Lantibiotics exhibit antimicrobial activity against a variety of pathogenic bacteria, for example, Staphylococcus aureus.[1] Subsequent to ribosomal peptide synthesis (RPS) peptides are posttranslationally modified. In the case of lantibiotics the amino acids Ser/Cys and Thr/Cys form the thioether-containing amino acids Lan and MeLan, respectively (Scheme 1).[2] Attempts to broaden the structural diversity of such peptides are limited by the restriction of ribosomal peptide synthesis (RPS) to the set of 20 canonical amino acids (cAAs). While the viability of total synthesis approaches to such peptides, albeit artful, is limited,[3] semisynthetic modifications only with easily accessible functional groups have been exploited, and site-directed mutagenesis approaches have also met with restricted success.[4] Expressed protein ligation (EPL) allows the generation of semisynthetic proteins with an almost unlimited number of noncanonical amino acids (ncAAs).[5] Although the intrinsic limitation that ncAAs are delivered only to the peptide part of the target protein could be overcome, as recently shown by Benkovic and Schultz,[6] the product yields of this procedure are extremely low. In contrast, the residuespecific replacement of amino acids,[7] which generally does not suffer from such drawbacks, is a more promising strategy to achieve efficient chemical diversification by directly translating various ncAAs into bioactive peptides. Recently, possibilities for lanthionine formation in cellfree translation systems (in vitro) have been reported,[8] whereas we, and others, succeeded in the expression of lantibiotics by RPS in Gram-negative Escherichia coli as a heterologous host.[9, 10] This bacterial host is, to date, the most efficient platform for genetic code engineering by which one or more types of ncAAs are cotranslationally incorporated into the target polypeptide sequences.[11] Therefore, it should be possible to employ recombinant expression for theScheme 1. Expansion of the synthetic possibilities for the design of ribosomal peptide antibiotics by an expanded amino acid repertoire. Reprogrammed in vivo synthesis of lantibiotics includes three levels of chemical diversification: 1) cotranslational, by insertion of various ncAAs, including some with unique chemical handles, 2) posttranslational, that is, enzymatic processing and assembly of characteristic lanthionines (Lan, MeLan), and 3) postbiosynthetic, enabling the tailoring of the lantibiotics’ structures by bioorthogonal conjugations under physiological conditions (eg attachment of various ligands such as chromophores and pharmacophores by click chemistry).