Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States.
J Am Chem Soc. 2021 Jan 20;143(2):623-627. doi: 10.1021/jacs.0c11113. Epub 2021 Jan 7.
Antibiotics to treat drug-resistant Gram-negative infections are urgently needed but challenging to discover. Using a cell-based screen, we identified a simple secondary amine that inhibited the growth of wild-type and but not the growth of the Gram-positive organism . Resistance mutations in and mapped exclusively to the aminoacyl-tRNA synthetase PheRS. We confirmed biochemically that the compound inhibited PheRS from these organisms and showed that it did not inhibit PheRS from or humans. To understand the basis for the compound's high selectivity for only some PheRS enzymes, we solved crystal structures of and PheRS complexed with the inhibitor. The structures showed that the compound's benzyl group mimics the benzyl of phenylalanine. The other amine substituent, a 2-(cyclohexen-1-yl)ethyl group, induces a hydrophobic pocket in which it binds. Through bioinformatic analysis and mutagenesis, we show that the ability to induce a complementary hydrophobic pocket that can accommodate the second substituent explains the high selectivity of this remarkably simple molecular scaffold for Gram-negative PheRS. Because this secondary amine scaffold is active against wild-type Gram-negative pathogens but is not cytotoxic to mammalian cells, we suggest that it may be possible to develop it for use in combination antibiotic therapy to treat Gram-negative infections.
我们需要迫切开发能够治疗耐药革兰氏阴性感染的抗生素，但这极具挑战性。我们使用基于细胞的筛选方法，发现了一种简单的仲胺，它可以抑制野生型和的生长，但不能抑制革兰氏阳性菌的生长。和中的耐药突变仅映射到氨酰-tRNA 合成酶 PheRS。我们通过生化实验证实该化合物抑制了这些生物体的 PheRS，并表明它不抑制来自或人类的 PheRS。为了了解该化合物对仅某些 PheRS 酶具有高选择性的基础，我们解决了与抑制剂复合的和 PheRS 的晶体结构。这些结构表明，该化合物的苄基基团模拟了苯丙氨酸的苄基。另一个胺取代基，2-（环己烯-1-基）乙基基团，诱导一个疏水性口袋，其中它结合。通过生物信息学分析和突变，我们表明，诱导互补疏水性口袋的能力可以容纳第二个取代基，这解释了这种非常简单的分子支架对革兰氏阴性 PheRS 的高选择性。由于这种仲胺支架对野生型革兰氏阴性病原体有效，但对哺乳动物细胞没有细胞毒性，我们建议可以开发它用于联合抗生素治疗以治疗革兰氏阴性感染。
