Collaborative Research: Acquisition of nitrogenase metal cofactors in soils: role of metallophores and limitation of N2-fixation

合作研究：土壤中固氮酶金属辅助因子的获取：金属团的作用和固氮的限制

• 批准号: 1024545
• 负责人: Anthony Aufdenkampe
• 金额: $ 3.4万
• 依托单位: Stroud Water Research Center
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1024545&HistoricalAwards=false
• 关键词: Collaborative; Research; Acquisition; nitrogenase; metal

Intellectual merit: N2 fixation is effected exclusively by bacteria and archea using the enzyme nitrogenase, which contains Fe and Mo as metal cofactors in its most active form, and Fe and V, or Fe-only in its alternative forms. The aim of this project is to elucidate how the mechanisms and kinetics of bacterial acquisition of Fe, Mo and V from soils may limit or control N2 fixation rates. N2-fixing bacteria produce siderophores (or ?iron carriers?) to bind iron in the external medium and take up the resulting Fe-siderophore complexes. Our recent work has shown that the siderophores are actually ?metallophores? used in the uptake of Mo and V, along with Fe. The biological acquisition of the various nitrogenase metal cofactors thus depends on their binding by bacterial metallophores. This project is organized around two major hypotheses: 1. Free-living N2-fixing bacteria excrete metallophores that are particularly efficient at capturing the metal (Mo, V or Fe) that is limiting N2 fixation; 2. Because of both competition with other metals for metallophore binding and scarcity in soils, Mo is inherently difficult to acquire and free-living N2-fixing bacteria often use alternative nitrogenases, particularly the V-nitrogenase, to fix N2. These hypotheses will be tested through a combination of laboratory and field experiments. Field studies will focus on sites where Mo may be limiting and employ molecular biological techniques to identify alternative nitrogenases.Broader Impacts: One postdoctoral researcher, one graduate student and several undergraduates will work on this project and be mentored by the PIs. Students from the local junior colleges will participate in the summer field research. The PIs will participate in the Quest summer program for school teachers.

智力优点：N2固定是通过细菌和ARCHEA使用酶氮酶以最活跃的形式的金属辅因子以及Fe和V的金属辅因子的，或以其替代形式的Fe-fe-fe。该项目的目的是阐明从土壤中对Fe，Mo和V细菌获取的机制和动力学如何限制或控制N2固定速率。 N2固定细菌产生铁载体（或？铁载体？）以结合外部培养基中的铁并占用所得的Fe-Sidenophore复合物。我们最近的工作表明铁载体实际上是金属载体？用于MO和V的摄取，以及Fe。因此，各种氮酶金属辅助因子的生物学获取取决于它们通过细菌金属粒子的结合。该项目围绕两个主要的假设进行组织：1。自由培养的N2固定细菌排泄金属团，在捕获限制N2固定的金属（MO，V或Fe）方面特别有效。 2。由于两种与其他金属的竞争有关金属结合和土壤中稀缺性的竞争，所以MO本质上难以获取和自由生活的N2固定细菌经常使用替代氮酶，尤其是V-硝基酶来修复N2。这些假设将通过实验室和现场实验的组合进行检验。现场研究将集中在MO可能受到限制并采用分子生物学技术来识别替代氮酶的地点上。Boader的影响：一名博士后研究人员，一名研究生和几名本科生将在该项目上工作，并由PIS进行指导。来自当地初中的学生将参加夏季野外研究。 PI将参加学校教师的Quest Summer计划。