A Bioinorganic Approach to Anthrax Lethal Factor Inhibitors

描述（由申请人提供）：本提案的主要目标是通过使用综合生物无机方法开发炭疽致死因子（LF）的新型抑制剂，该方法允许对抑制剂-金属蛋白相互作用的机制进行阐明。LF是一种水解锌依赖的金属酶，在炭疽芽孢杆菌的发病机制中起着重要作用。缺乏LF的炭疽杆菌菌株致病性降低，使该蛋白成为炭疽主要毒力因子的候选蛋白。抗毒素治疗对于补充抗生素治疗至关重要，由于炭疽的无症状性质，后者往往施用得太晚。几个小组已经开始研究LF的小分子抑制剂作为治疗炭疽爆发的途径。由于国际社会对生物战和生物恐怖主义的担忧，这一领域出现了复苏。其中最有希望的LF抑制剂是先前设计的基质金属蛋白酶（MMP）抑制剂，因为MMPs和LF在活性位点都含有催化锌（II）离子，可以直接与这些抑制剂结合，从而抑制催化活性。这一共同的基序导致使用MMP抑制剂作为LF抑制剂并取得令人鼓舞的结果。羟肟酸为基础的MMP抑制剂，构成了目前可用化合物的绝大多数，由于口服有效性低、药代动力学差和副作用（如肌肉骨骼疼痛），在临床试验中一直不成功。这种失败在很大程度上是由于羟基肟酸对锌的选择性和亲和力较低，以及羟基肟酸基团在体内的化学稳定性差。尽管MMP抑制剂作为LF抑制剂显示出巨大的前景，但仍然需要新的化合物，特别是那些提供羟肟酸金属螯合剂替代品的化合物。利用一种新的基于模型的机制方法，利用合成、生化和计算方法来揭示药物-金属蛋白相互作用是以下建议的重点。几种化合物被提出作为羟肟酸的替代品，并已显示出对炭疽LF的增强效力。初步结果表明，基于我们的设计策略的LF抑制剂是有效的，可溶的，选择性的，并且能够保护巨噬细胞免受炭疽致死毒素的侵害。该方法的进一步改进有望产生更有效的LF抑制剂。拟议的项目涉及发现新的化合物来解决炭疽的威胁。分子将被设计和合成来攻击炭疽细菌产生的一种关键毒素。通过这种方式，将开发出治疗炭疽爆发的创新疗法。

DESCRIPTION (provided by applicant): The major objective of this proposal is to develop novel inhibitors of anthrax lethal factor (LF) by using a comprehensive bioinorganic approach that allows for the mechanistic elucidation of inhibitor-metalloprotein interaction. LF is a hydrolytic zinc-dependent metalloenzyme that is known to play a prominent role in the pathogenesis of Bacillus anthracis. Strains of B. anthracis that are deficient in LF have reduced pathogenicity, making this protein a candidate as the lead virulence factor of anthrax. Anti-toxin therapies are essential to compliment antibiotic treatments, the latter of which are often administered too late due to the asymptomatic nature of anthrax. Several groups have begun to investigate small molecule inhibitors of LF as a route to therapeutics for treating anthrax breakouts. A resurgence in this area has occurred due to international concerns over biowarfare and bioterrorism. Among the most promising inhibitors for LF are previously devised matrix metalloproteinase (MMP) inhibitors, because both MMPs and LF contain a catalytic zinc(II) ion at the active site, which can be directly bound by these inhibitors, thereby suppressing catalytic activity. This common motif has led to the use of MMP inhibitors as inhibitors of LF with encouraging results. Hydroxamic acid-based MMP inhibitors, which make up the vast majority of currently available compounds, have been unsuccessful in clinical trials due to low oral availability, poor pharmacokinetics, and side effects such as musculoskeletal pain. This failure has been due in large part to the low selectivity and affinity of the hydroxamic acid for zinc and the poor chemical stability of the hydroxamic acid group in vivo. Although MMP inhibitors show great promise as LF inhibitors, there remains a need for new compounds, particularly those that provide alternatives to the hydroxamic acid metal chelator. The utilization of a new model-based mechanistic approach that employs synthetic, biochemical, and computational methods to reveal drug-metalloprotein interactions is the focus of the following proposal. Several compounds are proposed as alternatives to hydroxamic acids and have been shown to display improved potency against anthrax LF. Preliminary results show that a LF inhibitor based on our design strategy is potent, soluble, selective, and capable of protecting macrophage cells from anthrax lethal toxin. Further refinement of this approach is expected to yield even more effective LF inhibitors. The proposed project involves the discovery of new compounds to address the threat of anthrax. Molecules will be designed and synthesized to attack a key toxin produced by the anthrax bacteria. In this way, innovative therapeutics for treating anthrax outbreaks will be developed.