Targeting the PlsX/Y pathway for novel antimicrobials

为了开发新的抗菌药物发现靶点，我们最近发现革兰氏阳性菌使用一种独特且必需的途径来合成其膜磷脂，该途径由两种基因产物PlsX和PlsY介导。该途径通过PlsX产生独特的酰基磷酸中间体，然后将其用作PlsY的底物。PlsY是一种必需的酰基转移酶，没有哺乳动物同源物。使用生物电子等排的方法，我们设计了一些不可水解的模拟物的酰基磷酸盐中间体。当针对一组代表性革兰氏阳性病原体进行测试时，这些化合物仅显示出适度的抗微生物活性，B除外。炭疽菌（Sterne菌株）。为了证实这一结果，我们随后针对一组毒性B测试了这些化合物。炭疽菌菌株，所有这些菌株对我们最好的抑制剂高度敏感，产生与现有抗生素相当的MIC活性。我们认为这是发展选择性B的理想起点。炭疽抑制剂，这将是探索在这个赠款。本研究有3个具体目标：（i）合成一组扩展的抑制剂，并优化先导化合物的抗炭疽活性和潜在的口服生物利用度;（ii）生物化学评价B的抑制作用。（iii）对新出现的先导化合物进行微生物学评估，包括测试抗B.炭疽活性我们研究的终点将更好地理解这一重要的生物学途径，并确定它是否是抗菌药物发现的合适靶点。

In an effort to develop new targets for antibacterial drug discovery, we recently discovered that Gram positive bacteria use a unique and essential pathway to synthesize their membrane phospholipids mediated by two gene products, PlsX and PlsY. This pathway generates a unique acyl-phosphate intermediate via PlsX that is then utilized as a substrate for PlsY. PlsY is an essential acyltransferase and there are no mammalian homologs. Using a bioisosteric approach we designed a number of nonhydrolyzable mimics of the acyl-phosphate intermediate. When tested against a panel of representative gram positive pathogens these compounds showed only modest antimicrobial activity, with the exception of B. anthracis (Sterne strain) that was potently inhibited. To confirm this result we then tested these compounds against a panel of virulent B. anthracis strains, all of which were highly sensitive to our best inhibitors yielding comparable MIC activity to existing antibiotics. We believe that this is an ideal starting point for the development of selective B. anthracis inhibitors, which will be explored in this grant. This study has 3 specific aims: (i) To synthesize an expanded set of inhibitors and to optimize the lead compounds with respect to anti-anthracis activity and for potential oral bioavailability; (ii) to biochemically evaluate the inhibition of the B. anthracis PlsY enzymes by the newly synthesized inhibitors; (iii) To perform a microbiological assessment on the emerging lead compounds, including testing for anti-B. anthracis activity. The end point of our studies will produce a better understanding of this important biological pathway and determine whether it is a suitable target for antibacterial drug discovery.