Discovering New Anti-Infective Agents from Lysobacter

描述(申请人提供)：多重耐药已成为人类死亡和发病的一个日益重要的原因。发现新的抗感染药物是一种迫切而持续的需求。生物活性天然产物是抗感染药物的主要来源。传统上，土壤细菌，特别是革兰氏阳性链霉菌，一直是生物活性天然产物的主要来源。然而，许多普遍存在的土壤和水的居民，如革兰氏阴性滑行细菌Lysobacter，尽管它们是天然产品的多产者，但在很大程度上仍未被开发。该提案描述了一项从新来源发现和评估具有新结构和有效活性的新抗感染药物的研究计划。重点是破译它们的生物合成和调控机制。具体地说，将对两组生物活性天然产品HSAF和WAP-8294A进行调查。二氢麦芽酚(HSAF)是一种多环四酸大内酰胺(PTM)，代表了一种新型的抗真菌化合物，具有新的化学结构和新的作用机制。为了开发HSAF作为一种新型的抗真菌抗生素，了解这种新的化学结构的生物合成机理是非常重要的。HSAF生物合成基因簇只包含一个单模块聚酮合成酶-非核糖体肽合成酶(PKS/NRPS)，两侧有六种氧化还原酶的级联，尽管HSAF生物合成显然需要两个独立的六酮链，它们通过一个氨基酸(鸟氨酸)通过两个酰胺键连接在一起。这一系统代表了前所未有的PKS/NRPS混合迭代。这里的目标是说明“氧化还原酶调节的迭代PKS/NRPS”催化的反应，这些反应导致了不同的PTM结构。WAP-8294A是由至少20个环脂多肽组成的复合体，对耐甲氧西林金黄色葡萄球菌(耐甲氧西林金黄色葡萄球菌，ED5014倍于万古霉素的ED5014倍)具有很强的抗药性。由于产量非常低，只有复合体的主要成分WAP-8294A2正在进行临床研究(由aRigen制药公司)。尽管这些化合物是在近15年前首次分离出来的，其中一种正在进行临床研究，但它们的生物合成基因直到2011年才被发现。这里的目标是确定WAP生物合成和调节的分子机制，特别是导致结构多样性的脂肪酸掺入机制。了解HSAF和WAP-8294A的生物合成和调控机制是进行合理的生物合成工程、提高生产率和优化这两类非常有前景的生物活性天然产物的关键步骤。此外，由于溶杆菌是尚未被开发的高产天然产物，本研究将为发现新的抗感染药物开辟新的方向。 公共卫生相关性：由于多重耐药性的惊人增加，开发新的抗感染药物是人类健康的迫切和持续的需要。这项研究旨在通过从基本上未被开发的来源Lysobacter中发现新的抗生素天然产品来满足这一需求。对这些具有独特结构和生物活性的产品的生物合成机制的破译将有助于设计合理的策略，以开发作为新的抗感染药物的产品。

DESCRIPTION (provided by applicant): Multi-drug resistance has become an increasingly important cause of mortality and morbidity in humans. It is a pressing and continual need to discover new anti-infective agents. Bioactive natural products are a major source of anti-infective drugs. Traditionally, soil bacteria, especially the Gram-positive Streptomyces, have been the primary source for bioactive natural products. However, many ubiquitous inhabitants of soil and water, such as the Gram-negative gliding bacteria Lysobacter, remain largely unexplored, even though they are prolific producers of natural products. This proposal describes a research plan to discover and evaluate new anti-infectives with novel structures and potent activities from the new sources. The focus is on deciphering their biosynthetic and regulatory mechanisms. Specifically, two groups of bioactive natural products, HSAF and WAP-8294A, will be investigated. HSAF (dihydromaltophilin) is a polycyclic tetramate macrolactam (PTM) and represents a novel type of antifungal compounds with new chemistry and new mode of action. To develop HSAF as a new type of antifungal antibiotics, it is important to understand the biosynthetic mechanism for the novel chemical structure. The HSAF biosynthetic gene cluster contains only a single-module polyketide synthase-nonribosomal peptide synthetase (PKS/NRPS), flanked by a cascade of six redox enzymes, although HSAF biosynthesis apparently requires two separate hexaketide chains that are linked together by one amino acid (ornithine) via two amide bonds. This system represents an unprecedented iterative PKS/NRPS hybrid. The goal here is to illustrate the reactions catalyzed by the "redox enzymes-modulated iterative PKS/NRPS", which lead to the distinct PTM structure. WAP-8294A are a complex of at least 20 cyclic lipodepsipeptides with a potent activity against Methicillin-Resistant Staphylococcus aureus (MRSA, ED5014 times more active than vancomycin, a "last resort" antibiotic). Due to a very low yield, only the major component of the complex, WAP-8294A2, is in clinical studies (by aRigen Pharmaceuticals). Although the compounds were first isolated nearly 15 years ago and one of them is in clinical studies, their biosynthetic genes were just identified in 2011. The goal here is to determine the molecular mechanisms for WAP biosynthesis and regulation, particularly the mechanism for fatty acid incorporation that leads to structural diversity. The understanding of the biosynthetic and regulatory mechanisms for HSAF and WAP-8294A is an essential step toward rational biosynthetic engineering, productivity improvement and structure-activity optimization of these two groups of very promising bioactive natural products. In addition, because Lysobacter are prolific natural product producers that have not been exploited, this research will open a new direction to discovering new anti-infective drugs. PUBLIC HEALTH RELEVANCE: Developing new anti-infective drugs is a pressing and continual need for human health due to the alarming increase of multi-drug resistance. This research aims to address the need through discovering new antibiotic natural products from a largely unexplored source, Lysobacter. The deciphering of the biosynthetic mechanism for these structurally distinct and biologically active products will allow for designing rational strategiesin the development of the products as new anti-infectives.