Clustered genes required for synthesis and deposition of envelope glycolipids in Anabaena sp strain PCC 7120
Clustered genes required for synthesis and deposition of envelope glycolipids in Anabaena sp strain PCC 7120
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DOI：
10.1111/j.1365-2958.2005.04818.x
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发表时间：
2005-10-01
影响因子：
3.6
通讯作者：
Tabata, S
中科院分区：
文献类型：
--
作者：
Fan, Q;Huang, GC;Tabata, S
异形胞蓝藻对氮素的光还原具有重要的生态学意义和水稻自给农业意义。如果固氮酶要保持活性以在含氧环境中固定氮素(Fox(+)表型)，它们的杂囊必须有一个糖脂包膜层来限制氧的进入。丝状蓝藻的alr5354(HgID)、alr5355(HgIC)和alr5357(HgIB)基因。杂胞被膜糖脂的合成需要PCC7120菌株和发菜的hglE。新发现的Fox(-)突变体在附近的开放阅读框(ORF)all5343、all5345-asr5349和alr5351-alr5358中携带转座子。互补和其他分析提供的证据表明，至少ORF all5343(或共转录基因)、all5345、all5347、alr5348、asr5350-alr5353和alr5356也是Fox(+)表型所必需的，但不是asr5349。脂质和序列分析表明，alr5351-alr5357编码生物合成糖脂苷元的酶。电子显微镜显示all5345到all5347在糖脂的正常沉积中起作用。
Photoreduction of dinitrogen by heterocyst-forming cyanobacteria is of great importance ecologically and for subsistence rice agriculture. Their heterocysts must have a glycolipid envelope layer that limits the entry of oxygen if nitrogenase is to remain active to fix dinitrogen in an oxygen-containing milieu ( the Fox(+) phenotype). Genes alr5354 (hgID), alr5355 (hgIC) and alr5357 (hgIB) of the filamentous cyanobacterium, Anabaena sp. strain PCC 7120, and hglE of Nostoc punctiforme are required for synthesis of heterocyst envelope glycolipids. Newly identified Fox(-) mutants bear transposons in nearby open reading frames (orfs) all5343, all5345-asr5349 and alr5351-alr5358. Complementation and other analysis provide evidence that at least orfs all5343 (or a co-transcribed gene), all5345, all5347, alr5348, asr5350-alr5353 and alr5356, but not asr5349, are also required for a Fox(+) phenotype. Lipid and sequence analyses suggest that alr5351-alr5357 encode the enzymes that biosynthesize the glycolipid aglycones. Electron microscopy indicates a role of all5345 through all5347 in the normal deposition of the envelope glycolipids.