Radical strategies for inhibiting the antibiotic resistance protein, Cfr

描述(申请人提供)：细菌病原体中的抗生素耐药性正在上升，并正在成为全球健康危机。一种新出现的抗生素耐药机制是由CFR蛋白赋予的，它催化23S细菌rRNA中腺苷2503的碳8甲基化。令人担忧的是，这种简单的修饰使细菌对目前使用的多种针对核糖体的抗生素产生抗药性，包括苯尼醇、林可酰胺、恶唑烷酮类、胸膜多菌素、链球菌素A以及大环内酯类交沙霉素和螺旋霉素。此外，对利奈唑酮具有耐药性，这是一种合成的恶唑烷酮，用于由许多革兰氏阳性细菌引起的感染，包括耐万古霉素的肠球菌、耐甲氧西林的葡萄球菌和耐青霉素的链球菌，以及一些革兰氏阴性细菌。CFR使用一种独特的、依赖于自由基的机制来催化其靶标的甲基化，使用S-腺苷蛋氨酸作为附加甲基碳的来源和反应中的自由基引发剂。与所有其他依赖SAM的酶不同，CFR和它所在的酶家族的其他成员，被称为自由基SAM超家族，使用一种独特的铁离子[4Fe-4S]作为SAM的主要结合决定因素。这里描述的工作集中于产生CFR的抑制剂，这些抑制剂被设计成利用这种新的结合模式。策略包括基于结构的设计，这种设计由计算对接和高吞吐量方法提供信息。人们希望，一旦这些策略被证实适用于这类酶，这些最初的努力将成为更全面的工作的基础。显然，需要立即采取行动，以防止耐药性机制的进一步蔓延，该机制有能力削弱世界上与临床相关的抗生素武器库。

DESCRIPTION (provided by applicant): Antibiotic resistance among bacterial pathogens is on the rise, and is becoming a global health crisis. One emerging mechanism of antibiotic resistance is conferred by the Cfr protein, which catalyzes the methylation of carbon 8 of adenosine 2503 in 23S bacterial rRNA. Worryingly, this simple modification renders bacteria resistant to a number of classes of antibiotics currently in use that target the ribosome, includin phenicols, lincosamides, oxazolidinones, pleuromutilins, streptogramin A, and the macrolides josamycin and spiramycin. Moreover, resistance is conferred to linezolid, a synthetic oxazolidinone that is indicated for infections caused by a number of Gram-positive bacteria, including vancomycin-resistant enterococci, methicillin-resistant staphylococci, and penicillin-resistant streptococci, as well as some Gram-negative bacteria. Cfr uses a unique, radical-dependent, mechanism to catalyze methylation of its target, using S-adenosylmethionine (SAM) both as the source of the appended methyl carbon and as a radical initiator in the reaction. Unlike all other SAM- dependent enzymes, Cfr and other members of the family of enzymes in which it resides, dubbed the radical SAM superfamily, use a unique iron ion of a [4Fe-4S] as a major binding determinant for SAM. The work described herein focuses on generating inhibitors of Cfr that are engineered to take advantage of this novel binding mode. Strategies include structure-based design that is informed by computational docking as well as high throughput methods. It is hoped that these initial efforts will form the basis of a more comprehensive undertaking once these strategies are validated for this class of enzymes. It is clear that immediate action is required to prevent further spread of a resistance mechanism that has the ability to cripple the world's arsenal of clinically relevant antibiotics.