Biological nitrogen fixation by alternative nitrogenases in boreal cyanolichens: importance of molybdenum availability and implications for current biological nitrogen fixation estimates
Biological nitrogen fixation by alternative nitrogenases in boreal cyanolichens: importance of molybdenum availability and implications for current biological nitrogen fixation estimates
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DOI：
10.1111/nph.14166
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发表时间：
2017-01-01
期刊：
影响因子：
9.4
通讯作者：
Bellenger, Jean-Philippe
中科院分区：
文献类型：
--
作者：
Darnajoux, Romain;Zhang, Xinning;Bellenger, Jean-Philippe
隐花植物及其共生的蓝藻因其在氮循环中的重要作用而引起生态化学家的关注。生物固氮是由固氮酶介导的，在其最常见的形式中，需要钼在其活性位点。据报告，钼是许多生态系统（包括热带和温带森林）中生物固氮的限制性养分。最近的研究表明，替代固氮酶，即在其活性位点使用钒或铁代替钼，可能在自然生态系统中发挥比以前认识到的更突出的作用。钼的可用性对钒的收购和替代固氮酶的贡献，生物固氮在无处不在的cyanolichen Peltigera aphthosa s.l.的作用，我们证实了使用的替代钒基固氮酶在发菜cyanobiont这些地衣和它的实质性贡献生物固氮在这种生物体。我们还发现，钒的收购强烈调控的丰富的钼。这些研究结果表明，替代固氮酶不能再被忽视的自然生态系统中，特别是在贫金属限制的栖息地。
Cryptogamic species and their associated cyanobacteria have attracted the attention of biogeochemists because of their critical roles in the nitrogen cycle through symbiotic and asymbiotic biological fixation of nitrogen (BNF). BNF is mediated by the nitrogenase enzyme, which, in its most common form, requires molybdenum at its active site. Molybdenum has been reported as a limiting nutrient for BNF in many ecosystems, including tropical and temperate forests. Recent studies have suggested that alternative nitrogenases, which use vanadium or iron in place of molybdenum at their active site, might play a more prominent role in natural ecosystems than previously recognized.Here, we studied the occurrence of vanadium, the role of molybdenum availability on vanadium acquisition and the contribution of alternative nitrogenases to BNF in the ubiquitous cyanolichen Peltigera aphthosa s.l.We confirmed the use of the alternative vanadium-based nitrogenase in the Nostoc cyanobiont of these lichens and its substantial contribution to BNF in this organism. We also showed that the acquisition of vanadium is strongly regulated by the abundance of molybdenum.These findings show that alternative nitrogenase can no longer be neglected in natural ecosystems, particularly in molybdenum-limited habitats.