Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey.
Mikro Biyositemler Inc, 06530, Ankara, Turkey.
Arch Microbiol. 2019 Jul;201(5):661-671. doi: 10.1007/s00203-019-01635-x. Epub 2019 Feb 22.
This study investigated the effect of different nitrogen sources, namely, ammonium chloride and glutamate, on photoheterotrophic metabolism of Rhodobacter capsulatus grown on acetate as the carbon source. Genes that were significantly differentially expressed according to Affymetrix microarray data were categorized into Clusters of Orthologous Groups functional categories and those in acetate assimilation, hydrogen production, and photosynthetic electron transport pathways were analyzed in detail. Genes related to hydrogen production metabolism were significantly downregulated in cultures grown on ammonium chloride when compared to those grown on glutamate. In contrast, photosynthetic electron transport and acetate assimilation pathway genes were upregulated. In detail, aceA encoding isocitrate lyase, a unique enzyme of the glyoxylate cycle and ccrA encoding the rate limiting crotonyl-CoA carboxylase/reductase enzyme of ethylmalonyl-coA pathway were significantly upregulated. Our findings indicate for the first time that R. capsulatus can operate both glyoxylate and ethylmalonyl-coA cycles for acetate assimilation.
本研究考察了不同氮源，即氯化铵和谷氨酸，对以乙酸盐为碳源的荚膜红细菌的光异养代谢的影响。根据 Affymetrix 微阵列数据，显著差异表达的基因被归类为直系同源群功能类别，并且详细分析了在乙酸同化、产氢和光合电子传递途径中的基因。与在谷氨酸上生长的培养物相比，在氯化铵上生长的培养物中与产氢代谢相关的基因显著下调。相比之下，光合电子传递和乙酸同化途径的基因上调。具体而言，编码异柠檬酸裂解酶的 aceA 基因，该酶是乙醛酸循环的特有酶，以及编码丙二酰辅酶 A 途径限速酶丙二酰辅酶 A 羧化酶/还原酶的 ccrA 基因显著上调。我们的研究结果首次表明，荚膜红细菌可以同时运行乙醛酸循环和丙二酰辅酶 A 途径来同化乙酸盐。
