Regulation of bacterial manganese metabolism

细菌锰代谢的调节

基本信息

批准号：
8825518
负责人：
MARK R O'BRIAN
金额：
$ 28.48万
依托单位：
STATE UNIVERSITY OF NEW YORK AT BUFFALO
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-04-01 至 2018-04-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Manganese and the regulation of its acquisition and subsequent metabolism are important for normal cell function, and contribute to the success of bacteria in adapting to the diverse environments in which they occupy. Manganese can be a limiting nutrient, and thus manganese-dependent processes must be coordinated with availability of the metal. We are interested in understanding how Bradyrhizobium japonicum senses and acquires manganese, maintains homeostasis, and coordinates manganese-dependent activities with cellular levels. Preliminary evidence lead us to test the hypothesis that B. japonicum adapts to cellular manganese levels by novel mechanisms that differ substantially from that found in E. coli and other model organisms. B. japonicum belongs to the alpha-Proteobacteria, a diverse taxonomic group that includes numerous members that form close or intracellular associations with eukaryotic hosts in a symbiotic or pathogenic context. B. japonicum serves as a model organism to study related pathogens that are refractory to experimental analysis. Three specific aims are proposed. (1) Elucidate the mechanisms that maintain manganese homeostasis. We identified a high affinity outer membrane channel necessary for Mn2+ uptake. Outer membrane selectivity for a divalent ion is unprecedented and reveals a bacterial strategy for nutrient acquisition not previously appreciated. We will elucidate the role of this channel in manganese homeostasis. Moreover, B. japonicum tolerates an unusually high external manganese concentration that is toxic to other bacteria. We will determine the basis of this tolerance towards the goal of understanding how this organism maintains homeostasis. (2) Elucidate manganese-responsive transcriptional control via the B. japonicum Mur protein. B. japonicum has adapted a global bacterial iron-responsive transcriptional repressor to function as a Mn2+ responsive regulator. We uncovered novel aspects of the Mur protein. Firstly, it binds Mn2+ at a site dissimilar to the presumed metal binding sites of Fur family proteins, and resolving this issue should give insight as to how it has adapted to be a Mn2+ sensor. Secondly, the demetallated form of Mur is active and controls a different regulon than the Mn2+-loaded protein. We will analyze this novel function. (3) Determine the molecular basis for the integration of iron and manganese metabolism. Preliminary evidence shows that B. japonicum senses and responds to a simultaneous deficiency in both iron and manganese at the level of transcription that is qualitatively different from individual deficiencies in each metal. We will focus initially on two operons involved in branched chain amino acid degradation to gain insight into this global response.

描述（由申请人提供）：锰及其获取和随后的新陈代谢对正常细胞功能很重要，并有助于细菌在适应其占据的各种环境中的成功。锰可以是一种有限的营养素，因此必须与金属的可用性协调锰。我们有兴趣了解黄褐色的japonicum感官并获得锰，维持稳态，并与锰依赖性活性保持在细胞水平上。初步证据使我们检验了以下假设：Japonicum通过新型机制适应了细胞锰水平，这与大肠杆菌和其他模型生物体中的机制有很大不同。 Japonicum B.属于Alpha-甲状腺细菌，这是一个多样化的分类群，其中包括在共生或致病的环境下与真核宿主建立亲密或细胞内关联的众多成员。 japonicum是一种模型生物体，可研究对实验分析难治性的相关病原体。提出了三个具体目标。（1）阐明维持锰稳态的机制。我们确定了MN2+摄取所需的高亲和力外膜通道。二价离子的外膜选择性是前所未有的，并且揭示了以前不欣赏营养习得的细菌策略。我们将阐明该渠道在锰稳态中的作用。此外，Japonicum宽容耐用其他细菌毒性的异常高的外部锰浓度。我们将确定这种宽容的基础，以理解这种有机体如何保持体内平衡的目标。（2）通过Japonicum MUR蛋白阐明锰反应转录控制。 Japonicum B.已调整了全局细菌铁响应性转录阻遏物作为MN2+响应性调节剂的功能。我们发现了MUR蛋白的新颖方面。首先，它在位点上结合了MN2+与毛皮家族蛋白的假定金属结合位点不同，并且解决此问题应该可以洞悉它如何适应MN2+传感器。其次，MUR的分类形式是活性的，并且控制了与MN2+负载的蛋白质不同的调节子。我们将分析这一新功能。（3）确定铁和锰代谢整合的分子基础。初步证据表明，japonicum芽孢杆菌具有感官，并在转录水平上同时响应铁和锰的同时缺乏，这与每种金属的个体缺陷在质量上不同。我们最初将专注于两个参与分支链氨基酸降解的操纵子，以深入了解这种全球反应。