Mechanism and Inhibition for LuxS: A Biodefense Target

LuxS 的机制和抑制：生物防御目标

• 批准号: 6908135
• 负责人: ZHAOHUI SUNNY ZHOU
• 金额: $ 28.71万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6908135
• 关键词: X ray crystallography; aldehyde lyase; analog; antibacterial agents; bacteria infection mechanism; bacterial toxins; biofilm; bioterrorism /chemical warfare; chemical synthesis; drug resistance; enzyme activity; enzyme inhibitors; enzyme substrate; high performance liquid chromatography; isomerase; ketones; lyase; mass spectrometry; quorum sensing; synthetic enzyme; virulence

DESCRIPTION (provided by applicant): Bacterial infections, particularly those emerging with antibiotic resistance, pose an alarming threat to public health. Our long-term objective is to identify, characterize and validate new antibacterial targets. Traditional antibiotics act by killing or inhibiting bacteria, hence inducing antibiotic resistance. It is therefore imperative to explore alternative or complementary approaches. In the past few years, the ubiquitous bacterial enzyme LuxS has been found to play diverse and pivotal roles in bacterial quorum sensing, virulence regulation, toxin secretion and biofilm formation. In addition, central metabolic roles for LuxS are also proposed. This enzyme is found in Category A pathogens, including B. anthracis and Yersinia pestis; and in Category B pathogens, including Vibrio cholerae, Salmonella and diarrheagenic E. coil. Absent in humans, LuxS is an attractive target for anti-infective agent development. The enzymatic mechanism of LuxS remains elusive. Based on our preliminary studies, we propose that LuxS possesses functions of both an aldose-ketose isomerase and a lyase. The dual function of LuxS is mechanistically intriguing. Our proposed mechanism involves an initial aldose-ketose isomerization to generate a ketone at the C3 position on the carbohydrate moiety, and a final beta-elimination to cleave the C-S bond in S-ribosylhomocysteine. Our Specific Aim 1 is to chemically synthesize the proposed intermediates and their analogs, and test them as LuxS substrates or inhibitors. We will also attempt to trap or directly observe the proposed intermediates. Our Specific Aims 2 and 3 are to investigate the catalytic roles of Glu57 and Cys84 in B. subtilis LuxS by mutagenesis and chemical rescue, and the biological relevance of Cys84 oxidation. Lastly, we plan to design, synthesize and test mechanism-based inhibitors for LuxS, particularly those interacting with the active site zinc ion. We will also investigate how halogenated furanones, a group of natural antibacterial agents, inactivates LuxS, particularly for the V. cholerae enzyme. Additionally, we will test the effects of LuxS inhibitors on quorum sensing, biofilm formation and related bacterial physiology.

描述（由申请人提供）：细菌感染，尤其是患有抗生素耐药性的细菌感染对公共卫生构成令人震惊的威胁。我们的长期目标是识别，表征和验证新的抗菌靶标。传统的抗生素通过杀死或抑制细菌，从而诱导抗生素耐药性。因此，必须探索替代或互补方法。在过去的几年中，无处不在的细菌酶lux在细菌群体传感，毒力调节，毒素分泌和生物膜形成中起多种多样的关键作用。此外，还提出了中央代谢作用。该酶在A类病原体中发现，包括炭疽芽孢杆菌和耶尔森氏菌；在B类病原体中，包括弧菌霍乱，沙门氏菌和腹泻E.卷。在人类中，Luxs是抗感染剂开发的有吸引力的目标。 Lux的酶促机制仍然难以捉摸。根据我们的初步研究，我们建议Luxs具有醛糖酮异构酶和裂解酶的功能。 Luxs的双重功能在机械上很有趣。我们提出的机制涉及最初的醛酮异构化，以在碳水化合物部分的C3位置产生酮，以及最终的β-脱纤维，以在s-核糖基胚氨酸中裂解C-S键。我们的特定目的1是化学合成所提出的中间体及其类似物，并将其作为LuxS底物或抑制剂测试。我们还将尝试陷阱或直接观察所提出的中间体。我们的具体目的2和3是通过诱变和化学救援研究Glu57和Cys84在枯草芽孢杆菌中的催化作用，以及Cys84氧化的生物学相关性。最后，我们计划设计，合成和测试基于lux的抑制剂，尤其是那些与活性位点锌离子相互作用的抑制剂。我们还将研究一组天然抗菌剂的卤素如何使lux灭活，特别是对于霍乱葡萄球菌。此外，我们将测试Lux抑制剂对法规传感，生物膜形成和相关细菌生理学的影响。