Graph-Based Analysis of the Metabolic Exchanges between Two Co-Resident Intracellular Symbionts, Baumannia cicadellinicola and Sulcia muelleri, with Their Insect Host, Homalodisca coagulata
Graph-Based Analysis of the Metabolic Exchanges between Two Co-Resident Intracellular Symbionts, Baumannia cicadellinicola and Sulcia muelleri, with Their Insect Host, Homalodisca coagulata
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DOI：
10.1371/journal.pcbi.1000904
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发表时间：
2010-09-01
影响因子：
4.3
通讯作者：
Sagot, Marie-France
中科院分区：
文献类型：
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作者：
Cottret, Ludovic;Milreu, Paulo Vieira;Sagot, Marie-France
来自不同物种的内共生细菌可以生活在同一真核生物的细胞内。代谢交换发生在宿主和细菌之间，也发生在不同的内吞生物体之间。由于两者都有完整的基因组注释，我们建立了两种内共生细菌Sulcia muelleri和Baumannia cicadellinicola的代谢网络，它们生活在神枪手Homalodisca coagulata的特定细胞内，并研究了涉及三个之间碳原子转移的代谢交换。我们自动确定了两个代谢网络的潜在外源获得的代谢物（种子）集。我们表明，这两种细菌在碳代谢中所需的种子数量大大减少。而且，两种代谢网络只有三种种子是共同的，这表明两种代谢的互补性不仅表现在每种细菌的代谢能力上，还表现在它们对同一环境的不同利用上。此外，我们的研究结果表明，S。muelleri可能完全独立于B的代谢网络。蝉生相反，后者的碳代谢似乎依赖于S的代谢。muelleri，至少两种必需氨基酸，苏氨酸和赖氨酸。接下来，为了定义种子的哪些子集（前体集）足以产生参与共生功能的代谢物，我们使用了我们最近开发的基于图形的方法PITUFO。我们的研究结果高度完善了我们的知识之间的互补性代谢的两种细菌和他们的主机。因此，我们表明种子，似乎强制性的代谢产物的合成参与共生功能。我们的研究结果表明，这两个B。cicadellinicola和S. Muelleri可以完全独立于由共存的内吞生物体提供的代谢物以产生提供给共生系统的代谢物的碳骨架（即，thr和lys仅被B利用。cicadellinicola生产其蛋白质）。
Endosymbiotic bacteria from different species can live inside cells of the same eukaryotic organism. Metabolic exchanges occur between host and bacteria but also between different endocytobionts. Since a complete genome annotation is available for both, we built the metabolic network of two endosymbiotic bacteria, Sulcia muelleri and Baumannia cicadellinicola, that live inside specific cells of the sharpshooter Homalodisca coagulata and studied the metabolic exchanges involving transfers of carbon atoms between the three. We automatically determined the set of metabolites potentially exogenously acquired (seeds) for both metabolic networks. We show that the number of seeds needed by both bacteria in the carbon metabolism is extremely reduced. Moreover, only three seeds are common to both metabolic networks, indicating that the complementarity of the two metabolisms is not only manifested in the metabolic capabilities of each bacterium, but also by their different use of the same environment. Furthermore, our results show that the carbon metabolism of S. muelleri may be completely independent of the metabolic network of B. cicadellinicola. On the contrary, the carbon metabolism of the latter appears dependent on the metabolism of S. muelleri, at least for two essential amino acids, threonine and lysine. Next, in order to define which subsets of seeds (precursor sets) are sufficient to produce the metabolites involved in a symbiotic function, we used a graph-based method, PITUFO, that we recently developed. Our results highly refine our knowledge about the complementarity between the metabolisms of the two bacteria and their host. We thus indicate seeds that appear obligatory in the synthesis of metabolites are involved in the symbiotic function. Our results suggest both B. cicadellinicola and S. muelleri may be completely independent of the metabolites provided by the co-resident endocytobiont to produce the carbon backbone of the metabolites provided to the symbiotic system (i.e., thr and lys are only exploited by B. cicadellinicola to produce its proteins).