Toward a Chemo-Enzymatic Synthesis of Vancomycin and Its Analogs

摘要 糖肽抗生素(GPA)是世界上最重要的治疗药物之一。这个 万古霉素是这个天然产品家族的创始成员，是治疗感染的最后手段。 耐甲氧西林金黄色葡萄球菌(MRSA)和艰难梭菌。以及其他几个人 抗生素，万古霉素提供了对抗超级细菌的重要武器，超级细菌是具有 对多种临床抗生素产生获得性耐药。但随着对这最后一道防线的抵抗蔓延，它 开发化学剪裁万古霉素和其他GPA的方法以创造新的 对抗已知抗性机制的衍生品。 合成衍生化已被证明是创造新抗生素的一种成功方法，但这 这种方法在GPA内受到严格限制，主要是因为它们的化学复杂性和规模。解决问题的关键 万古霉素的结构复杂性和生物活性是由两个芳基组成的三个芳香族交联物 乙醚连接和二芳基碳-碳键。过去20年的研究表明， 细胞色素P450酶(OxyB)安装了第一个芳基醚键。剩余的两个交联链的起源， 然而，仍然难以捉摸。我们最近发现，第二种P450酶OxyA引入了第二种 万古霉素生物合成过程中的芳醚交联剂。我们进一步概括了OxyC的酶活性和 表明它安装了最终的联芳基连接，这是该反应在任何GPA中的第一次演示。此外， 我们利用天然生物合成金属酶的反应能力来实现一种化学-酶 合成万古霉素苷元衍生物的路线。这一阶段将充分利用这种化学-酶 化学衍生万古霉素的方法，希望产生有用的第二代衍生品。 在目前的应用中，我们建议不仅完成万古霉素的化学-酶合成， 而且是已知保持生物活性的衍生物，即使是对抗药性病原体也是如此。我们进一步建议 建立一个万古霉素类似物的文库，我们将其称为“设计者万古霉素”，其中包含以下修饰 用当前的方法是无法获得的。我们将同时探索详细的化学机理 并创建了一种创新的固相方法，以增强我们的化学- 酶法路线。我们的研究将揭示万古霉素的生物合成，并使最大 尚未全面努力创造具有独特结构和可能的新生物活性的GPA变体 精美的化学-酶法路线。

ABSTRACT Glycopeptide antibiotics (GPAs) are among the most important therapeutic agents world-wide. The founding member of this natural product family, vancomycin, is used a drug of last resort against infections by methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. Along with a handful of other antibiotics, vancomycin provides an important weapon against “superbugs”, pathogenic bacteria that have acquired resistance to multiple clinical antibiotics. But as resistance to even this last line of defense spreads, it is ever more important to develop means of chemically tailoring vancomycin and other GPAs to create new derivatives that counter known resistance mechanisms. Synthetic derivatization has proven to be a successful method for creating new antibiotics, but this approach is severely restricted within the GPAs, primarily due to their chemical complexity and size. Key to the structural complexity and biological activity of vancomycin are three aromatic crosslinks, consisting of two aryl ether connections and a biaryl carbon-carbon bond. Research over the past 20 years has shown that a cytochrome P450 enzyme (OxyB) installs the first aryl ether bond. The origin of the remaining two crosslinks, however, remained elusive. We recently showed that OxyA, a second P450 enzyme, introduces the second aryl ether crosslink during vancomycin biogenesis. We further recapitulated the enzymatic activity of OxyC and showed that it installs the final biaryl connection, the first demonstration of this reaction in any GPA. Moreover, we have exploited the reactivities of the native biosynthetic metalloenzymes to implement a chemo-enzymatic route for creating a vancomycin aglycone derivative. The stage is set to fully leverage this chemo-enzymatic approach to chemically derivatize vancomycin in the hopes of generating useful second-generation derivatives. In the current application, we propose to complete the chemo-enzymatic synthesis of not just vancomycin, but also of derivatives known to retain bioactivity, even against resistant pathogens. We further propose to build a library of vancomycin analogs that we refer to as “designer vancomycins”, containing modifications that are inaccessible with current methodologies. We will simultaneously explore the detailed chemical mechanism of OxyB and create an innovative solid-phase approach to enhance the efficiency and scalability of our chemo- enzymatic route. Our studies will shed light onto the biosynthesis of vancomycin and enable the most comprehensive effort yet to create GPA variants with unique structures and possibly new bioactivities via an elegant chemo-enzymatic route.