Study of heme uptake and transport proteins from P. aerugenosa and S. dysenteriae

铜绿假单胞菌和痢疾杆菌血红素摄取和转运蛋白的研究

• 批准号: 8075320
• 负责人: Kenton Rodgers
• 金额: $ 2.19万
• 依托单位: NORTH DAKOTA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8075320
• 关键词: Address; Affinity; Antibiotic Resistance; Assimilations; Bacterial Infections; Binding; Carrier Proteins; Cells; Chemistry; Complex; Environment; Exhibits; Free Energy; Frequencies; Genetic; Glutathione S-Transferase; Goals; Health; Heme; Heme Iron; Hemoglobin; Human; Infection; Iron; Kinetics; Knowledge; Ligands; Molecular; Organism; Oxygenases; Process; Proteins; Pseudomonas; Pseudomonas aeruginosa; Role; Shigella dysenteriae; Source; Specificity; Stretching; Surface; System; Thermodynamics; Toxic effect; Work; alternative treatment; base; cytotoxic; design; driving force; heme receptor; heme-binding protein; interest; meetings; mutant; pathogen; receptor; uptake

DESCRIPTION (provided by applicant): Recent genetic characterization of bacterial heme uptake and transport systems in Pseudomonas aerugenosa and Shigella dysenteriae have raised interesting questions regarding the functional details of heme binding, translocation, and release by the protein players, the heme-binding proteins (HBPs) and the heme-transport receptors (HTRs), in these processes. Many gram negative bacterial pathogens use the most abundant source of soluble iron, heme from their host, as a source of the iron essential to establish infection. However, heme is cytotoxic and must be highly sequestered throughout the course of uptake and transport. This requirement for protection against the toxicity of heme imposes two design criteria on the proteins involved in the process. The first is that, in order to protect the organism from the toxic effects of free heme, all heme:HBP and heme:HTR complexes must exhibit intrinsically high thermodynamic stabilities. Yet, facile transfer of heme between these proteins having high heme affinities must be possible. Thus the second design criterion is that it must be possible to modulate the high stabilities of the heme:HBPs and heme:HTRs through specific interactions with the partners to which they pass their cargo. The free energy of interaction between heme-loaded proteins and their targets must be transduced to impose driving force and kinetic lability on the transfer of heme from the donor to its target, i.e. effective direction of heme to HO for liberation of its iron can be viewed as being mechanistically driven. Work on bacterial assimilation of the iron from heme along with our recent biophysical characterization of some of the proteins involved suggests that the HBPs can be classified in three groups; those having anionic tyrosinate axial ligands, those having axial His ligands, and those having axial His and Met ligands. In this study, the HBPs and HTRs from S. dysenteriae and P. aerugenosa will be examined. Based on genetic studies, the proteins involved in heme uptake and transport have been identified. The general hypothesis to be addressed by this proposed study is that the aforementioned axial ligand environments correlate with distinct mechanisms for heme binding, transport, and release in the aforementioned organisms. We will identify contribution(s) from heme coordination chemistry to the stabilities of the heme:HBP and heme:HTR complexes. We will further investigate which of those contributions could be modulated by complexation of heme:HBP or heme:HTR with its target protein for heme transfer. The long-term goal of our work with heme uptake and transport proteins is to elucidate the mechanistic parameters that govern the specificity and efficacy of heme transfer. The relevance of this work to human health lies in the potential of the results to ultimately provide new inroads into treatment of bacterial infections. In this project, the means by which bacterial pathogens acquire heme from their hosts and assimilate the iron necessary to establish infection will be investigated at the level of molecular mechanism. The relevance of this work to human health lies in the potential for knowledge of heme uptake by bacterial pathogens to ultimately provide new inroads into treatment of bacterial infections.

描述（由申请人提供）：铜绿假单胞菌和志贺氏菌中细菌血红素摄取和转运系统的最新遗传表征提出了关于血红素结合、易位和蛋白质参与者（血红素结合蛋白（HBPs）和血红素转运受体（HTR））在这些过程中释放的功能细节的有趣问题。许多革兰氏阴性细菌病原体使用来自其宿主的最丰富的可溶性铁来源血红素作为建立感染所必需的铁来源。然而，血红素是细胞毒性的，并且必须在整个摄取和运输过程中高度隔离。这种对血红素毒性的保护要求对参与该过程的蛋白质施加了两个设计标准。首先，为了保护生物体免受游离血红素的毒性作用，所有血红素：HBP和血红素：HTR复合物必须表现出固有的高热力学稳定性。然而，血红素在这些具有高血红素亲和力的蛋白质之间的容易转移必须是可能的。因此，第二个设计标准是，必须有可能通过与它们传递其货物的伴侣的特异性相互作用来调节血红素：HBP和血红素：HTR的高稳定性。负载血红素的蛋白质与其靶点之间相互作用的自由能必须被转换，以在血红素从供体转移到其靶点时施加驱动力和动力学不稳定性，即有效引导血红素到HO以释放其铁可以被视为是机械驱动的。关于细菌从血红素中同化铁的工作沿着以及我们最近对所涉及的一些蛋白质的生物物理表征表明，HBP可以分为三组：具有阴离子酪氨酸轴向配体的HBP、具有轴向His配体的HBP以及具有轴向His和Met配体的HBP。本研究对S.将检查P.aerugenosa和P.aerugenae。基于遗传学研究，已经鉴定了参与血红素摄取和运输的蛋白质。这项研究提出的一般假设是，上述轴向配体环境与上述生物体中血红素结合，运输和释放的不同机制相关。我们将确定血红素配位化学对血红素：HBP和血红素：HTR复合物稳定性的贡献。我们将进一步研究这些贡献中的哪些可以通过血红素：HBP或血红素：HTR与其用于血红素转移的靶蛋白的络合来调节。我们对血红素摄取和转运蛋白研究的长期目标是阐明控制血红素转运特异性和有效性的机制参数。这项工作与人类健康的相关性在于结果最终为细菌感染的治疗提供新的进展。在本项目中，将在分子机制水平上研究细菌病原体从其宿主获得血红素并同化建立感染所需的铁的手段。这项工作与人类健康的相关性在于细菌病原体对血红素摄取的了解，最终为细菌感染的治疗提供新的进展。