Regulation of bacterial manganese metabolism

细菌锰代谢的调节

• 批准号: 9266051
• 负责人: MARK R O'BRIAN
• 金额: $ 9.55万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 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
• 来源: https://reporter.nih.gov/project-details/9266051
• 关键词: Affinity; Alphaproteobacteria; Animal Model; Bacteria; Binding; Bradyrhizobium; Branched-Chain Amino Acids; Cell physiology; Environment; Escherichia coli; Eukaryota; Genetic Transcription; Goals; Homeostasis; Individual; Ion Channel; Ions; Iron; Lead; Manganese; Membrane; Membrane Transport Proteins; Metabolic Control; Metabolism; Metal Binding Site; Metals; Modeling; Molecular; Normal Cell; Nutrient; Operon; Organism; Process; Prokaryotic Cells; Protein Family; Proteins; Refractory; Regulation; Regulon; Role; Site; Testing; Transcription Repressor/Corepressor; Transcriptional Regulation; active control; base; experimental analysis; insight; interest; iron metabolism; member; novel; pathogen; response; sensor; success; uptake

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）：锰及其获取和随后代谢的调节对于正常细胞功能很重要，并有助于细菌成功适应其所处的不同环境。锰可能是一种限制性营养素，因此依赖锰的过程必须与金属的可用性相协调。我们有兴趣了解日本慢生根瘤菌如何感知和获取锰、维持体内平衡以及在细胞水平上协调锰依赖性活动。初步证据引导我们检验日本芽孢杆菌通过与大肠杆菌和其他模式生物中发现的机制有很大不同的新机制来适应细胞锰水平的假设。日本芽孢杆菌属于α-变形菌门，这是一个多样化的分类群，包括许多在共生或致病环境中与真核宿主形成密切或细胞内关联的成员。日本芽孢杆菌作为模式生物来研究难以进行实验分析的相关病原体。 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。外膜对二价离子的选择性是前所未有的，揭示了细菌获取营养物质的策略，这是以前未曾认识到的。我们将阐明该通道在锰稳态中的作用。此外，日本芽孢杆菌能耐受异常高的外部锰浓度，这对其他细菌有毒。我们将确定这种耐受性的基础，以期了解这种生物体如何维持体内平衡。 (2) 通过日本芽孢杆菌 Mur 蛋白阐明锰响应性转录控制。 B. japonicum 已经改造了一种全局细菌铁反应性转录阻遏蛋白，以充当 Mn2+ 反应性调节剂。我们发现了 Mur 蛋白的新奇之处。首先，它在与推测的 Fur 家族蛋白金属结合位点不同的位点结合 Mn2+，解决这个问题应该可以深入了解它如何适应成为 Mn2+ 传感器。其次，Mur 的去金属形式具有活性，并且控制着与 Mn2+ 负载蛋白不同的调节子。我们将分析这个新颖的功能。 (3)确定铁、锰代谢整合的分子基础。初步证据表明，日本芽孢杆菌在转录水平上感知并响应铁和锰的同时缺乏，这与每种金属的单独缺乏有质的不同。我们将首先关注参与支链氨基酸降解的两个操纵子，以深入了解这种全局反应。

项目成果

Magnesium-dependent processes are targets of bacterial manganese toxicity.

• DOI: 10.1111/mmi.12687
• 发表时间: 2014-08
• 期刊: Molecular microbiology
• 影响因子: 3.6
• 作者: Hohle TH;O'Brian MR
• 通讯作者: O'Brian MR

Synthetic Lethality of the bfr and mbfA Genes Reveals a Functional Relationship between Iron Storage and Iron Export in Managing Stress Responses in Bradyrhizobium japonicum.

• DOI: 10.1371/journal.pone.0157250
• 发表时间: 2016
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Sankari S;O'Brian MR
• 通讯作者: O'Brian MR

Differential control of Bradyrhizobium japonicum iron stimulon genes through variable affinity of the iron response regulator (Irr) for target gene promoters and selective loss of activator function.

通过铁反应调节剂 (Irr) 对靶基因启动子的可变亲和力和激活子功能的选择性丧失来差异控制日本慢生根瘤菌铁刺激基因。

• DOI: 10.1111/mmi.12584
• 发表时间: 2014
• 期刊: Molecular microbiology
• 影响因子: 3.6
• 作者: Jaggavarapu,Siddharth;O'Brian,MarkR
• 通讯作者: O'Brian,MarkR

Redox-Dependent Dynamics in Heme-Bound Bacterial Iron Response Regulator (Irr) Protein.

血红素结合细菌铁反应调节蛋白 (Irr) 的氧化还原依赖性动力学。

• DOI: 10.1021/acs.biochem.6b00512
• 发表时间: 2016
• 期刊: Biochemistry
• 影响因子: 2.9
• 作者: Kobayashi,Kazuo;Nakagaki,Megumi;Ishikawa,Haruto;Iwai,Kazuhiro;O'Brian,MarkR;Ishimori,Koichiro
• 通讯作者: Ishimori,Koichiro

Manganese is required for oxidative metabolism in unstressed Bradyrhizobium japonicum cells.

• DOI: 10.1111/j.1365-2958.2012.08057.x
• 发表时间: 2012-05
• 期刊: Molecular microbiology
• 影响因子: 3.6
• 作者: Hohle TH;O'Brian MR
• 通讯作者: O'Brian MR