The rice field cyanobacteria Anabaena azotica and Anabaena sp CH1 express vanadium-dependent nitrogenase
The rice field cyanobacteria Anabaena azotica and Anabaena sp CH1 express vanadium-dependent nitrogenase
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DOI：
10.1007/s00203-006-0150-4
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发表时间：
2006-11-01
影响因子：
2.8
通讯作者：
Bothe, Hermann
中科院分区：
文献类型：
--
作者：
Boison, Gudrun;Steingen, Caroline;Bothe, Hermann
固氮鱼腥藻（Anabaena azotica）FACHB-118和鱼腥藻（Anabaena sp. CH 1）是从中国和台湾稻田中分离的异囊蓝藻，在缺钼条件下表达含钒固氮酶。这是第二次直接观察到蓝细菌中的替代固氮酶。钒固氮酶特异性基因vnfDG融合和聚类在系统发育树旁边的甲烷八叠球菌的相应基因。通过对来自A. azotica和Anabaena sp. CH 1. vnfH序列与变异鱼腥藻（Anabaena variabilis）的vnfH序列聚簇。vnf基因强烈转录，只有在文化中生长的无钼培养基中，或在含W培养基中，但也弱含钼培养基。NifH在所有培养基中转录。无钼乙炔还原反应的在线测量。固氮菌培养证明V-固氮酶是活性的。乙烷以乙烯的2.1%的速率连续形成。无论有无钼，乙炔还原培养物的最适高温为42.5 ℃。在无钼培养基中，hupL基因与vnfDG基因在A. azotica、Anabaena sp. CH 1和A.变异性。
Anabaena azotica FACHB-118 and Anabaena sp. CH1, heterocystous cyanobacteria isolated from Chinese and Taiwanese rice fields, expressed vanadium-containing nitrogenase when under molybdenum deficiency. This is the second direct observation of an alternative nitrogenase in cyanobacteria. The vanadium nitrogenase-specific genes vnfDG are fused and clustered in a phylogenetic tree next to the corresponding genes of Methanosarcina. The expression of vnfH in cells cultured in Mo-free medium and of nifH in Mo-grown cells was shown for the first time by sequencing cDNA derived from cultures of A. azotica and Anabaena sp. CH1. The vnfH sequences clustered with that of Anabaena variabilis. The vnf genes were strongly transcribed only in cultures grown either in Mo-free medium, or in W-containing medium, but also weakly in Mo-containing medium. NifH was transcribed in all media. On-line measurements of acetylene reduction by Mo-free A. azotica cultures demonstrated that the V-nitrogenase was active. Ethane was formed continuously at a rate of 2.1% of that of ethylene. Acetylene reduction of cultures grown either with or without Mo had a high temperature optimum of 42.5 degrees C. The uptake hydrogenase gene hupL was expressed in Mo-free medium concomitantly with vnfDG in A. azotica, Anabaena sp. CH1, and A. variabilis.