Dynamic diel proteome and daytime nitrogenase activity supports buoyancy in the cyanobacterium Trichodesmium.
Dynamic diel proteome and daytime nitrogenase activity supports buoyancy in the cyanobacterium Trichodesmium.
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DOI：
10.1038/s41564-021-01028-1
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发表时间：
2022-02
影响因子：
28.3
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中科院分区：
文献类型：
--
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Trichodesmium属的蓝藻每天向海洋表面提供约80 Tg的固定氮，并有助于海洋生物地球化学，包括二氧化碳（CO2）的封存。木霉在日光下固定氮，尽管在光合作用中产生的氧与氮酶不相容。虽然保护氮酶的机制尚不清楚，但所有提出的策略都需要大量的资源投资。在这里，我们确定了木霉属植物白天固氮的一个关键好处，可能抵消这些成本。我们分析了养殖种群和野外种群的蛋白质组学，并与夜间固氮的海洋重氮营养动物鳄鱼（Crocosphaera watsonii sp. WH8501）进行了比较。木霉的蛋白质组具有极强的动态性，同时进行光合作用和固氮，导致颗粒有机碳（POC）和颗粒有机氮（PON）的平衡生产。与产生大量糖原作为氮酶能量储存的鳄鱼不同，蛋白质组学证据与Trichodesmium通过PsaC充电的可溶性铁氧还蛋白直接向氮酶提供能量，从而减少了产生糖原的需要。这最大限度地减少了与糖原相关的压舱物，降低了细胞密度，降低了下沉速度，从而支持了Trichodesmium作为一种浮力强、适应强光、形成集落的蓝藻的生态位。为了占据同时进行固氮和光合作用的生态位，木霉似乎已经放弃了自己作为铁的明显消费者的地位，因此发展了独特的铁获取策略，包括使用富含铁的粉尘。悬浮菌群对颗粒的捕获可能会增加光区内矿物铁的停留时间和降解。这些发现描述了细胞生物化学如何定义和加强这些重要的海洋重氮营养体的生态和生物地球化学功能。
Cyanobacteria of the genus Trichodesmium provide about 80 Tg of fixed nitrogen to the surface ocean per day and contribute to marine biogeochemistry including the sequestration of carbon dioxide (CO2). Trichodesmium fixes nitrogen in the daylight, despite the incompatibility of the nitrogenase enzyme with oxygen produced during photosynthesis. While the mechanisms protecting nitrogenase remain unclear, all proposed strategies require considerable resource investment. Here we identify a crucial benefit of daytime nitrogen fixation in Trichodesmium spp. that may counteract these costs. We analyzed diel proteomes of cultured and field populations of Trichodesmium in comparison to the marine diazotroph Crocosphaera watsonii sp. WH8501, which fixes nitrogen at night. Trichodesmium’s proteome was extraordinarily dynamic and demonstrated simultaneous photosynthesis and nitrogen fixation, resulting in balanced particulate organic carbon (POC) and particulate organic nitrogen (PON) production. Unlike Crocosphaera, which produces large quantities of glycogen as an energy store for nitrogenase, proteomic evidence is consistent with the idea that Trichodesmium reduces the need to produce glycogen by supplying energy directly to nitrogenase via soluble ferredoxin charged by PsaC. This minimizes ballast associated with glycogen, reducing cell density and decreasing sinking velocity, thus supporting Trichodesmium’s niche as a buoyant, high-light adapted, colony forming cyanobacterium. In order to occupy its niche of simultaneous nitrogen fixation and photosynthesis, Trichodesmium appears to have resigned itself to being a conspicuous consumer of iron, and has therefore developed unique iron acquisition strategies including the use of iron-rich dust. Particle capture by buoyant Trichodesmium colonies may increase the residence time and degradation of mineral iron in the euphotic zone. These findings describe how cellular biochemistry defines and reinforces the ecological and biogeochemical function of these keystone marine diazotrophs.
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影响因子：
16.6
作者：
Buchanan, Pearse J.;Chase, Zanna;Bindoff, Nathaniel L.
通讯作者：
Bindoff, Nathaniel L.
影响因子：
6.4
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
56.9
作者：
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通讯作者：
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