The central role of the host cell in symbiotic nitrogen metabolism.
The central role of the host cell in symbiotic nitrogen metabolism.
复制标题
宿主细胞在共生氮代谢中的核心作用。
DOI：
10.1098/rspb.2012.0414
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Macdonald SJ
中科院分区：
文献类型：
--
作者：
Macdonald SJ
共生氮循环使动物能够在氮缺乏的饮食和环境中茁壮成长。它传统上是指共生微生物利用动物废弃物中的氮来合成必需氨基酸（EAA），并将其转运回动物宿主。我们应用代谢建模和补充代谢产物分析，研究氮循环之间的共生关系豌豆蚜虫和细胞内bacteriumBuchnera，合成EAA。这一结果在两个重要方面不同于传统的氮循环概念。首先，蚜虫排出的氨主要由宿主细胞（细菌细胞）而不是布赫内拉菌再循环。宿主细胞循环是由四种EAA的共同生物合成途径介导的，其中蚜虫转氨酶将氨衍生的氮掺入Buchnerto合成的碳骨架中以产生EAA。第二，用于氮再循环的氨底物来自细菌细胞代谢，使得共生体不是来自其他蚜虫器官的含氮废物的库。宿主细胞介导的氮循环可能是普遍的昆虫共生体与共享的EAA生物合成途径所产生的共生体基因介导的EAA合成的终端反应的损失。
Symbiotic nitrogen recycling enables animals to thrive on nitrogen-poor diets and environments. It traditionally refers to the utilization of animal waste nitrogen by symbiotic micro-organisms to synthesize essential amino acids (EAAs), which are translocated back to the animal host. We applied metabolic modelling and complementary metabolite profiling to investigate nitrogen recycling in the symbiosis between the pea aphid and the intracellular bacteriumBuchnera, which synthesizes EAAs. The results differ from traditional notions of nitrogen recycling in two important respects. First, aphid waste ammonia is recycled predominantly by the host cell (bacteriocyte) and notBuchnera. Host cell recycling is mediated by shared biosynthetic pathways for four EAAs, in which aphid transaminases incorporate ammonia-derived nitrogen into carbon skeletons synthesized byBuchnerato generate EAAs. Second, the ammonia substrate for nitrogen recycling is derived from bacteriocyte metabolism, such that the symbiosis is not a sink for nitrogenous waste from other aphid organs. Host cell-mediated nitrogen recycling may be general among insect symbioses with shared EAA biosynthetic pathways generated by the loss of symbiont genes mediating terminal reactions in EAA synthesis.