Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme
Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacterium Nostoc punctiforme
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DOI：
10.1073/pnas.1419543112
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发表时间：
2015-02-10
影响因子：
11.1
通讯作者：
Dittmann, Elke
中科院分区：
文献类型：
--
作者：
Liaimer, Anton;Helfrich, Eric J. N.;Dittmann, Elke
点状念珠藻是一种多功能的蓝藻，可以独立生活，也可以与不同类群的植物共生。植物和N. punctiforme分别刺激或抑制感染性运动丝的分化，称为hormogonia。我们利用聚酮合酶突变体，积累了大量的激素作为一种工具，以了解次生代谢产物对细胞分化的N。点状的应用MALDI成像来说明次级代谢组的重编程，诺斯替内酯被鉴定为pks 2（-）突变分泌组中的主要差异。随后的分化测定和可视化的细胞类型特异性表达的nostopeptolides通过转录报告菌株提供的证据nostopeptolides的多方面的作用，无论是作为一个自生hormogonium抑制因子或作为一种化学引诱物，这取决于其细胞外浓度。虽然nostopeptolide是组成性表达的自由生活状态，分泌水平动态变化之前，期间和之后的Hormogonium分化阶段。代谢产物被发现是严格下调与Gunnera manicata和Blasia pusilla共生，而其他代谢产物的上调，通过MALDI成像证明，表明植物调节N.点状的
Nostoc punctiforme is a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants and N. punctiforme were shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation of N. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in the pks2(-) mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis with Gunnera manicata and Blasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites within N. punctiforme.