Ariyakumaran Rishikesh, Pokrovskaya Varvara, Little Dustin J, Howell P Lynne, Nitz Mark
Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada).
Program in Molecular Structure and Function, The Hospital for Sick Children and Department of Biochemistry, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8 (Canada).
Chembiochem. 2015 Jun 15;16(9):1350-6. doi: 10.1002/cbic.201500091. Epub 2015 May 26.
De-N-acetylases of β-(1→6)-D-N-acetylglucosamine polymers (PNAG) and β-(1→4)-D-N-acetylglucosamine residues in peptidoglycan are attractive targets for antimicrobial agents. PNAG de-N-acetylases are necessary for biofilm formation in numerous pathogenic bacteria. Peptidoglycan de-N-acetylation facilitates bacterial evasion of innate immune defenses. To target these enzymes, transition-state analogue inhibitors containing a methylphosphonamidate have been synthesized through a direct Staudinger-phosphonite reaction. The inhibitors were tested on purified PgaB, a PNAG de-N-acetylase from Escherichia coli, and PgdA, a peptidoglycan de-N-acetylase from Streptococcus pneumonia. Herein, we describe the most potent inhibitor of peptidoglycan de-N-acetylases reported to date (Ki =80 μM). The minimal inhibition of PgaB observed provides insight into key structural and functional differences in these enzymes that will need to be considered during the development of future inhibitors.
β-（1→6）-D- $N$-乙酰葡糖胺聚合物（PNAG）和肽聚糖中β-（1→4）-D- $N$-乙酰葡糖胺残基的脱 $N$-乙酰化酶是抗菌剂的理想作用靶点。PNAG脱 $N$-乙酰化酶是众多病原菌生物膜形成所必需的。肽聚糖脱 $N$-乙酰化有助于细菌逃避天然免疫防御。为了作用于这些酶，通过直接施陶丁格-亚磷酸酯反应合成了含有甲基膦酰胺酸酯的过渡态类似物抑制剂。这些抑制剂在纯化的PgaB（一种来自大肠杆菌的PNAG脱 $N$-乙酰化酶）和PgdA（一种来自肺炎链球菌的肽聚糖脱 $N$-乙酰化酶）上进行了测试。在此，我们描述了迄今为止报道的最有效的肽聚糖脱 $N$-乙酰化酶抑制剂（ $K_i$ = 80 μM）。观察到的对PgaB的最小抑制作用为这些酶的关键结构和功能差异提供了见解，这在未来抑制剂的开发过程中需要加以考虑。
