Mechanisms of Metal Ion Homeostasis of Oral Streptococci

摘要 锌（Zn）是所有生命形式的必需微量金属，在高浓度下会变得有毒。因为它 具有抗菌和抗炎特性，锌被用作治疗剂来治疗各种 感染性和非感染性人类条件。虽然锌作为防龋剂的功效有点 有争议的是，锌盐用于几种口腔保健产品，以防止结石形成，治疗 牙龈炎和口臭，并控制牙菌斑积累。然而，上升的后果 唾液锌水平高于生理浓度对微生物和宿主-病原体相互作用的影响很小 了解并要求进一步调查。最近，我们发现S.变形杆菌，一种重要的病原体， 龋齿，本质上比其他链球菌，包括对锌的毒性作用更耐受 与口腔健康有关的物种。使用转录组和突变分析方法，我们确定了一个 以前未表征的P1 B型ATP酶出口和同源转录因子，我们分别 命名为ZccE和ZccR，是导致S.变异人搜索 公共数据库中，我们发现ZccE是唯一的S。变异体为发展提供了机会 锌为基础的抗菌治疗，专门针对消除S。变异人我们的假设是 克服锌毒的能力是S.变形杆菌的病理生理学， ZccE抑制剂的鉴定可以为开发物种特异性Zn基抑制剂铺平道路。 治疗方式考虑到开发新的防龋疗法的长期目标， 这一概念上，技术上和实践上的创新应用是：（一）揭示监管 介导S.（二）确定下列各项的影响： 增加锌浓度，高于生理水平，对口腔粘膜的组成和体内平衡 微生物组;和（iii）探索并开发ZccE作为抗微生物靶标。为了实现这些目标， PI组建了一个多学科的研究小组，在分子生物学方面具有互补的专业知识， 微生物学和动物模型（Abranches和Lemos），基于结构的计算机辅助药物设计（Li）， 和药物化学（Huigens和Li）。完成这项研究将：（一）大大促进我们的 了解调节机制和途径，介导细菌锌耐受性与 揭示新的治疗靶点的潜力;（ii）阐明锌基 口腔健康，更具体地说，在龋齿控制治疗;和（iii）促进合理设计的新的 抗微生物疗法以预防/控制致龋生物膜的出现。

ABSTRACT Zinc (Zn) is an essential trace metal to all forms of life that becomes toxic at high concentrations. Because it has both antimicrobial and anti-inflammatory properties, Zn is used as a therapeutic agent to treat a variety of infectious and non-infectious human conditions. While the efficacy of Zn as an anticaries agent is somewhat controversial, Zn salts are used in several oral healthcare products to prevent calculus formation, treat gingivitis and halitosis, and to control dental plaque accumulation. However, the consequences of rising salivary Zn levels above physiological concentrations to microbial and host-pathogen interactions are poorly understood and warrant further investigation. Recently, we discovered that S. mutans, a keystone pathogen in dental caries, is inherently more tolerant to the toxic effects of Zn than other streptococci, including commensal species associated with oral health. Using transcriptome and mutational analysis approaches, we identified a previously uncharacterized P1B-type ATPase exporter and cognate transcriptional factor, which we respectively named ZccE and ZccR, as primarily responsible for the remarkable high Zn tolerance of S. mutans. Searching public databases, we found that ZccE is unique to S. mutans providing an opportunity for the development of Zn-based antimicrobial therapies specifically tailored to eliminate S. mutans. Our working hypotheses are that the ability to overcome Zn toxicity is an important aspect of S. mutans pathophysiology, and that the identification of ZccE inhibitors can pave the way for the development of a species-specific Zn-based therapeutic modality. With the long-term goal of developing new anticaries therapies in mind, the specific goals of this conceptually, technically, and translationally innovative application are: (i) to uncover the regulatory mechanisms and pathways that mediate Zn tolerance in S. mutans; (ii) to determine the implications of increasing Zn concentrations, above physiological levels, to the composition and homeostasis of the oral microbiome; and (iii) to explore and then develop ZccE as an antimicrobial target. To accomplish these goals, the PI assembled a multidisciplinary team of investigators with complementary expertise in molecular microbiology and animal models (Abranches and Lemos), structured-based computer-aided drug design (Li), and medicinal chemistry (Huigens and Li). Completion of this study will: (i) significantly advance our understanding of the regulatory mechanisms and pathways that mediate bacterial Zn tolerance with the potential of revealing new therapeutic targets; (ii) shed light onto the implications and potential of Zn-based therapies in oral health and, more specifically, in caries control; and (iii) facilitate the rational design of new antimicrobial therapies to prevent/control the emergence of cariogenic biofilms.