Targeting the PlsX/Y pathway for novel antimicrobials

为了开发抗菌药物的新靶点，我们最近发现革兰氏阳性菌通过一种独特而必需的途径合成其膜磷脂，该途径由两个基因产物PlsX和PlsY介导。该途径通过PlsX产生一种独特的磷酸酰基中间体，然后作为PlsY的底物。PlsY是一种必需的酰基转移酶，在哺乳动物中没有同源物。利用生物等构方法，我们设计了一些磷酸酰基中间体的不可水解模拟物。当对一组具有代表性的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菌活性，除了炭疽杆菌（斯特恩菌株）被有效抑制外。为了证实这一结果，我们随后将这些化合物与一组毒性炭疽杆菌菌株进行了测试，所有这些菌株对我们最好的抑制剂都高度敏感，其MIC活性与现有抗生素相当。我们相信这是开发选择性炭疽杆菌抑制剂的理想起点，这将在本基金中进行探索。本研究有三个具体目标：(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）对新合成的抑制剂对炭疽芽孢杆菌PlsY酶的抑制作用进行生化评价；（iii）对新出现的先导化合物进行微生物学评估，包括抗b抗体测试。炭疽的活动。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.