Different levels of transcriptional regulation due to trophic constraints in the reduced genome of Buchnera aphidicola APS
Different levels of transcriptional regulation due to trophic constraints in the reduced genome of Buchnera aphidicola APS
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DOI：
10.1128/aem.01118-06
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发表时间：
2006-12-01
影响因子：
4.4
通讯作者：
Charles, Hubert
中科院分区：
文献类型：
--
作者：
Reymond, Nancie;Calevro, Federica;Charles, Hubert
涉及细胞内微生物和动物的共生协会是普遍的，特别是对于那些以不良或不平衡饮食为食的物种。蚜虫生布氏菌（Buchnera aphidicola）是一种专性胞内细菌，为蚜虫提供植物韧皮部汁液中紧缺的营养物质--必需氨基酸（EAAs）。Buchnera基因组在细胞内进化过程中经历了严重的减少。EAA生物合成的基因是保守的，但大多数转录调控元件丢失。这项工作解决了两个主要问题：是转录Buchnera（一）调节和（二）缩放到蚜虫EAA的需求？设计了两个微阵列实验用于分析Buchnera中的基因表达。第一个实验的特点是蚜虫饮食中酪氨酸和苯丙氨酸的特定消耗，第二个实验结合了蚜虫饮食中EAA的全球减少与蔗糖浓度的增加来操纵蚜虫的生长速率。进行蚜虫生物学性能和预算分析（由饮食提供的EAA与由Buchnera合成的EAA之间的平衡）以量化蚜虫对其共生细菌的营养需求。尽管没有已知的调控元件，一个显着的转录调控观察到在不同层次的组织在Buchnera基因组：基因之间，在假定的转录单位，并在特定的代谢途径。然而，明确的证据转录变化的EAA生物合成的缩放蚜虫的需求没有得到支持。布赫内拉的基因组减少的转录反应的表型相关性的解决。
Symbiotic associations involving intracellular microorganisms and animals are widespread, especially for species feeding on poor or unbalanced diets. Buchnera aphidicola, the obligate intracellular bacterium associated with most aphid species, provides its hosts with essential amino acids (EAAs), nutrients in short supply in the plant phloem sap. The Buchnera genome has undergone severe reductions during intracellular evolution. Genes for EAA biosynthesis are conserved, but most of the transcriptional regulatory elements are lost. This work addresses two main questions: is transcription in Buchnera (i) regulated and (ii) scaled to aphid EAA demand? Two microarray experiments were designed for profiling the gene expression in Buchnera. The first one was characterized by a specific depletion of tyrosine and phenylalanine in the aphid diet, and the second experiment combined a global diminution of EAAs in the aphid diet with a sucrose concentration increase to manipulate the aphid growth rate. Aphid biological performance and budget analysis (the balance between EAAs provided by the diet and those synthesized by Buchnera) were performed to quantify the nutritional demand from the aphids toward their symbiotic bacteria. Despite the absence of known regulatory elements, a significant transcriptional regulation was observed at different levels of organization in the Buchnera genome: between genes, within putative transcription units, and within specific metabolic pathways. However, unambiguous evidence for transcriptional changes underpinning the scaling of EAA biosynthesis to aphid demand was not obtained. The phenotypic relevance of the transcriptional response from the reduced genome of Buchnera is addressed.