Symbiont Models for Natural Product Pathway Manipulation

描述(申请人提供)：海洋无脊椎动物，如海绵、被囊动物和柳珊瑚，产生令人惊叹的多样性的次生代谢物，其中许多显示出作为药剂的前景。然而，为临床开发提供海洋天然产品一直是一个主要障碍，因为这些生物往往很少或很难收集。重组DNA技术提供了一种可能的策略，通过在细菌培养中表达生物合成基因来绕过供应问题，但有许多问题阻碍了这种方法的广泛使用。在海洋无脊椎动物体内发现的大量细菌多样性和全程表达的困难极大地阻碍了该方法的有效性。此外，通常很难设计出生产新的天然产品的途径。我们最近报道了第一个合理的全程鉴定和异源表达动物-细菌共生的海洋天然产物的例子。在海鞘的专性共生体--异丙氯隆中发现了一条编码形成盘状酰胺A和C的途径，并在大肠杆菌中进行了表达。在这个项目中，我们将利用这一早期的成功，从海洋环境中的各种共生组织中克隆和设计具有生物医学意义的重要天然产物途径。通过进一步探索这种模式共生系统，我们将建立和验证共生产品的通用克隆方法，开发目前正在进行临床或临床前试验的药物供应，并通过合理的途径工程发现新药。因此，这项研究将为海洋天然产物药物发现和开发中的问题提供切实可行的解决方案。

DESCRIPTION (provided by applicant): Marine invertebrates, such as sponges, tunicates, and gorgonians, produce a stunning diversity of secondary metabolites, many of which show promise as pharmaceutical agents. However, supplying marine natural products for clinical development has been a major hurdle, since the organisms are often rare or difficult to collect. Recombinant DNA technology offers a possible strategy to circumvent the supply problem by expression of biosynthetic genes in bacterial culture, but there are many problems that have prevented the widespread use of this approach. The large bacterial diversity found within marine invertebrates and the difficulty of whole pathway expression greatly hinder the usefulness of the approach. In addition, it is often difficult to engineer pathways to produce new natural products. We recently reported the first example of rational whole-pathway identification and heterologous expression for a marine natural product from an animal-bacterium symbiosis. A pathway encoding formation of patellamides A and C was identified in Prochloron, the obligate symbiont of an ascidian, and expressed in Escherichia coli. In this project, we will capitalize on this early success by cloning and engineering biomedically important natural product pathways from a variety of symbiotic associations in the marine environment. By further exploring this model symbiotic system, we will establish and validate methodology for the general cloning of symbiotic products, develop a supply of drugs that are currently in clinical or preclinical trials, and discover new drugs via rational pathway engineering. This study will thus provide practical solutions to problems in drug discovery and development with marine natural products.