School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
Department of Botany, School of Life Sciences, Mizoram University, Tanhril Campus, Aizawl 796004, India.
Microbiology (Reading). 2011 Mar;157(Pt 3):911-917. doi: 10.1099/mic.0.045682-0. Epub 2010 Dec 16.
This paper reports an investigation of salinity-induced glycolate metabolism in the cyanobacterium Anabaena sp. PCC 7120 (hereafter Anabaena PCC 7120). Quantitative analysis of transcripts for the photosynthesis-associated genes encoding ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), phosphoribulokinase and transketolase, as well as those involved in glycolate metabolism (phosphoglycolate phosphatase, glycolate oxidase, alanine-glyoxylate aminotransferase and serine hydroxymethyltransferase) was performed. The expression of all investigated photosynthesis-associated genes except Rubisco was downregulated after 24 h NaCl treatment. However, under the same conditions, the transcripts encoding enzymes involved in glycolate metabolism were overexpressed. This was further confirmed by the quantitative analysis of the intermediates involved in glycolate metabolism. The intracellular levels of organic acids (glyceric, glycolic and glyoxylic acids) and amino acids (glycine and serine) were elevated in salt-treated cells as compared to those in the control cells. Transcriptional inhibition of photosynthesis-associated genes, and upregulation of genes and enhanced synthesis of intermediates associated with glycolate metabolism, indicate the occurrence of this photorespiratory metabolic pathway metabolism in Anabaena PCC 7120 under salt stress.
本文报道了对蓝藻 Anabaena sp. PCC 7120（以下简称 Anabaena PCC 7120）中盐诱导的乙醇酸代谢的研究。对光合作用相关基因编码核酮糖-1,5-二磷酸羧化酶加氧酶（Rubisco）、磷酸核酮糖激酶和转酮醇酶，以及参与乙醇酸代谢的基因（磷酸乙醇酸磷酸酶、乙醇酸氧化酶、丙氨酸-乙醛酸氨基转移酶和丝氨酸羟甲基转移酶）的转录物进行了定量分析。在 24 小时 NaCl 处理后，除 Rubisco 外，所有研究的光合作用相关基因的表达均下调。然而，在相同条件下，参与乙醇酸代谢的酶的编码基因表达上调。这通过对参与乙醇酸代谢的中间产物的定量分析进一步得到证实。与对照细胞相比，盐处理细胞中有机酸（甘油酸、乙醇酸和乙醛酸）和氨基酸（甘氨酸和丝氨酸）的细胞内水平升高。光合作用相关基因的转录抑制，以及与乙醇酸代谢相关的基因上调和中间产物的合成增强，表明在盐胁迫下 Anabaena PCC 7120 中发生了这种光呼吸代谢途径代谢。
