Biosynthesis of Hypotensive Phosphonopeptide Natural Products

说明（由申请人提供）：来自放线菌的天然产物“K-26”是一类未研究的含有天然碳-磷键的化合物的代表，其结合了酪氨酸的膦酸类似物。K- 26具有血管紧张素转换酶（ACE）抑制活性，IC 50值为12.5 nM，与广泛使用的抗高血压药物Captopril相当。K-26由N-乙酰化异亮氨酸、酪氨酸和非蛋白氨基酸（R）-1-氨基-2-（4-羟基苯基）乙基膦酸（AHEP）组成。尽管K-26和相关化合物具有强的促炎活性，但K-26和更具体地AHEP生物合成的生物合成途径仍然未被表征。AHEP的芳香族氨基酸功能表明其起源在于莽草酸途径。然而，这是很难合理化的磷酸烯醇式丙酮酸酯，活动负责形成所有先前研究的含膦酸盐的天然产物，可以整合到经典的氨基酸代谢，以产生AHEP。我们描述的初步数据表明，AHEP是来自酪氨酸和C-P键形成化学是独特的。我们提出了一个C-P键形成机制的假设，并提出了一系列的研究：（1）确定K-26的基本结构单元和组装途径，（2）确定负责K-26生物合成的基因，（3）表征K-26的生物合成机制，特别是C-P键形成的生物化学。对公众健康的影响：拟议的研究将是第一次研究一类独特的含有芳香族膦酸的化合物的生物合成，这类化合物已被证明具有有效的金属蛋白酶抑制活性。因此，该提议将为发现和重组生物催化产生治疗上有用的新型膦酸酯功能性金属蛋白酶抑制剂提供重要的新工具。金属蛋白酶抑制剂具有治疗大量人类疾病的潜力，包括高血压、癌症和骨关节炎等。

DESCRIPTION (provided by applicant): The natural product 'K-26' from an actinomycete is representative of an uninvestigated class of natural carbon-phosphorus bond containing compounds which incorporate a phosphonic acid analog of tyrosine. K- 26 possesses angiotensin converting enzyme (ACE) inhibitory activity with an IC50 value of 12.5 nM, comparable to the widely prescribed antihypertensive drug Captopril. K-26 is comprised of N-acetylated isoleucine, tyrosine, and the nonproteinogenic amino acid, (R)-1-amino-2-(4-hydroxyphenyl)ethylphosphonic acid (AHEP). Despite the potent hypotensive activity of K-26 and related compounds, the biosynthetic pathways by which K-26 and more specifically AHEP are biosynthesized still remain uncharacterized. The aromatic amino acid functionality of AHEP suggests that its origin lies in the shikimic acid pathway. However, it is difficult to rationalize how phosphoenolpyruvate mutase, the activity responsible for forming all previously studied phosphonate containing natural products, can be integrated into classical amino acid metabolism to generate AHEP. We describe preliminary data that demonstrate that AHEP is derived from tyrosine and that the C-P bond forming chemistry is unique. We hypothesize a mechanism for C-P bond formation and propose a series of studies to (1) define the basic building blocks and pathway of assembly of K-26, (2) identify the genes responsible for K-26 biosynthesis and (3) characterize the K-26 biosynthetic machinery, especially the C-P bond forming biochemistry. Impact on public health: Proposed research will be the first study of the biosynthesis of a unique class of compounds containing an aromatic phosphonic acid, a class which has been demonstrated to have potent metalloproteinase inhibitory activity. As such, this proposal will provide significant new tools for the discovery and recombinant biocatalytic generation of therapeutically useful novel phosphonate functional metalloproteinase inhibitors. Metalloproteinase inhibitors have potential to treat a large number of human illnesses including hypertension, cancer and osteoarthritis, among others.