ABSTRACT
Inhibitors of 4′-phosphopantetheine adenylyltransferase (PPAT) were identified through high-throughput screening of the AstraZeneca compound library. One series, cycloalkyl pyrimidines, showed inhibition of PPAT isozymes from several species, with the most potent inhibition of enzymes from Gram-positive species. Mode-of-inhibition studies with
Streptococcus pneumoniae
and
Staphylococcus aureus
PPAT demonstrated representatives of this series to be reversible inhibitors competitive with phosphopantetheine and uncompetitive with ATP, binding to the enzyme-ATP complex. The potency of this series was optimized using structure-based design, and inhibition of cell growth of Gram-positive species was achieved. Mode-of-action studies, using generation of resistant mutants with targeted sequencing as well as constructs that overexpress PPAT, demonstrated that growth suppression was due to inhibition of PPAT. An effect on bacterial burden was demonstrated in mouse lung and thigh infection models, but further optimization of dosing requirements and compound properties is needed before these compounds can be considered for progress into clinical development. These studies validated PPAT as a novel target for antibacterial therapy.
摘要
通过对阿斯利康化合物库进行高通量筛选,发现了 4′-磷酸泛硫乙烯腺苷转移酶(PPAT)的抑制剂。其中一个系列的环烷基嘧啶对多个物种的 PPAT 同工酶有抑制作用,对革兰氏阳性物种的酶的抑制作用最强。对肺炎链球菌和
肺炎链球菌
和
金黄色葡萄球菌
PPAT 研究表明,该系列的代表药物是与磷酸泛硫乙胺竞争的可逆抑制剂,但与 ATP 并不竞争,而是与酶-ATP 复合物结合。利用基于结构的设计优化了该系列的效力,并实现了对革兰氏阳性菌细胞生长的抑制。通过靶向测序生成耐药突变体以及构建过表达 PPAT 的构建体,进行了作用模式研究,结果表明生长抑制是由于抑制了 PPAT。在小鼠肺部和大腿感染模型中证明了对细菌负担的影响,但在考虑将这些化合物推进临床开发之前,还需要进一步优化剂量要求和化合物特性。这些研究验证了 PPAT 是抗菌治疗的新靶点。