Glycopeptide Complexes with Bacterial Cell Walls by REDOR NMR

描述(申请人提供)：万古霉素通过干扰细胞壁的生物合成杀死革兰氏阳性肠球菌和葡萄球菌。我们已经证明，在野生型金黄色葡萄球菌中，万古霉素与细胞壁前体的茎末端结合，并抑制糖基化(糖链延伸)。近年来，出现了对万古霉素耐药的肠球菌和葡萄球菌。这些细菌改变了肽聚糖结构，减少了万古霉素的结合。我们已经使用固体核磁共振表征了五个氟化糖肽的细胞壁复合体，它们对万古霉素耐药肠球菌具有更好的效力。我们从礼来公司获得了两种药物，从俄罗斯新抗生素事业研究所获得了两种，还有一种是我们自己合成的。我们首次将这些药物的结构和活性联系起来，并制定了它们的作用模式。在下一个授权期，我们计划证明或反驳一般的假设，即这些药物通过干扰肽聚糖生物合成过程中的模板识别来杀死万古霉素耐药肠球菌和葡萄球菌。我们认为，新的肽链必须预先排序，以适应紧密交叉连接的三维网络，这就是为什么现有的最近邻链被用作合成新链的模板。我们将使用固态核磁共振检测各种对万古霉素敏感和耐药的肠球菌和葡萄球菌的药物复合体的形成和生物合成来测试这些概念，这些微生物是我们从同事P.Courvalin(法国)和H.Labischinski(德国)那里获得的。我们将使用高度选择性的稳定同位素标记协议，通过新的、特别设计的固态核磁共振实验进行检测。我们所检查的糖肽对万古霉素耐药肠球菌和葡萄球菌的效力得到改善，但由于有害副作用，没有一种糖肽在美国被批准用于临床。我们希望，本申请中提出的工作将导致对这些糖肽作用模式(S)的深入了解，这将刺激人们寻找副作用可耐受的新的、有效的抗生素。

DESCRIPTION (provided by applicant): Vancomycin kills Gram-positive enterococci and staphylococci by interfering with cell-wall biosynthesis. We have shown that in wild-type Staphylococcus aureus, vancomycin binds to the stem termini of cell-wall precursors and inhibits transglycosylation (glycan chain extension). Recently, vancomycin-resistant enterococci and staphylococci have emerged. These bacteria have altered peptidoglycan structures and reduced vancomycin binding. We have used solid-state NMR to characterize the cell-wall complexes of five fluorinated glycopeptides with improved potency against vancomycin-resistant enterococci. We obtained two of the drugs from Eli Lilly Company, two from the Cause Institute of New Antibiotics (Russia), and one we synthesized ourselves. We have correlated structure and activity for these drugs for the first time and have formulated their mode of action. In the next grant period, we plan to prove or disprove the general hypothesis, that these drugs kill vancomycin-resistant enterococci and staphylococci by interfering with template recognition during peptidoglycan biosynthesis. We believe that new peptidoglycan strands must be pre-ordered to fit into a tightly cross-linked three-dimensional network, and that this is the reason that an existing nearest-neighbor strand is used as a template for the synthesis of a new strand. We will test these notions using solid-state NMR detection of drug-complex formation and biosynthesis in whole cells of a variety of vancomycin-susceptible and vancomycin-resistant enterococci and staphylococci, organisms which we have acquired from our colleague- collaborators, P. Courvalin (France) and H. Labischinski (Germany). We will use highly selective stable-isotope labeling protocols with detection by new, specially designed solid-state NMR experiments. None of the glycopeptides with improved potency against vancomycin-resistant enterococci and staphylococci that we have examined are approved for clinical use in the United States because of deleterious side effects. We are hopeful that the insights into the mode(s) of action of these glycopeptides that will result from the work proposed in this application will stimulate the search for new and potent antibiotics with tolerable side effects.