The marine cyanobacterium Crocosphaera watsonii WH8501 synthesizes the compatible solute trehalose by a laterally acquired OtsAB fusion protein
The marine cyanobacterium Crocosphaera watsonii WH8501 synthesizes the compatible solute trehalose by a laterally acquired OtsAB fusion protein
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DOI：
10.1111/j.1462-2920.2012.02709.x
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发表时间：
2012-05-01
影响因子：
5.1
通讯作者：
Hagemann, Martin
中科院分区：
文献类型：
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作者：
Pade, Nadin;Compaore, Justine;Hagemann, Martin
相容溶质是小的有机分子，参与适应各种压力，例如温度和盐度。海洋或中度耐盐蓝藻积累葡萄糖基甘油，而低耐盐性蓝藻（淡水菌株）通常积累蔗糖或海藻糖作为主要相容性溶质。对海洋单细胞固氮蓝藻 Crocosphaera watsonii WH8501 基因组的筛选表明，发现了一种用于合成海藻糖的融合蛋白，而不是用于葡萄糖基甘油生物合成的基因，该融合蛋白与肠细菌中的海藻糖磷酸合酶和海藻糖磷酸酶（OtsAB 途径）相似。因此，鳄鱼细胞表现出盐刺激的 otsAB 基因表达以及盐依赖性海藻糖积累。重组全长 OtsAB 和截短 OtsB 版本的生化特征表明，Crocosphaera 中的 otsAB 基因编码活性海藻糖-磷酸合酶/磷酸酶融合蛋白。在其他蓝细菌的基因组中没有发现编码此类蛋白质的基因，但存在于许多其他不相关的海洋细菌中，这表明 otsAB 可能是通过横向基因转移到鳄鱼球菌基因组中获得的。
Compatible solutes are small organic molecules that are involved in the acclimation to various stresses such as temperature and salinity. Marine or moderate halotolerant cyanobacteria accumulate glucosylglycerol, while cyanobacteria with low salt tolerance (freshwater strains) usually accumulate sucrose or trehalose as the main compatible solutes. The screening of the genome of the marine, unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH8501 revealed that instead of genes for glucosylglycerol biosynthesis, a fusion protein for the synthesis of trehalose was found that displayed similarities to trehalose-phosphate-synthase and -phosphatase (OtsAB pathway) from enterobacteria. Accordingly, cells of Crocosphaera showed salt-stimulated expression of the otsAB gene as well as a salt-dependent trehalose accumulation. The biochemical characterization of recombinant full-length OtsAB and truncated OtsB versions revealed that the otsAB gene in Crocosphaera encodes for an active trehalose-phosphate-synthase/phosphatase fusion protein. Genes coding for such proteins were not found in the genomes of other cyanobacteria but were present in many other, non-related marine bacteria, suggesting that otsAB might have been acquired by lateral gene transfer into the Crocosphaera genome.