Long-term response toward inorganic carbon limitation in wild type and glycolate turnover mutants of the cyanobacterium Synechocystis sp strain PCC 68031[W]
Long-term response toward inorganic carbon limitation in wild type and glycolate turnover mutants of the cyanobacterium Synechocystis sp strain PCC 68031[W]
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DOI：
10.1104/pp.107.103341
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发表时间：
2007-08-01
期刊：
影响因子：
7.4
通讯作者：
Hagemann, Martin
中科院分区：
文献类型：
--
作者：
Eisenhut, Marion;Aguirre von Wobeser, Eneas;Hagemann, Martin
协同变化的转录模式和生理特性，导致长期（这里定义为长达24小时）的无机碳（C-I）的限制已经调查的蓝藻集胞藻属菌株PCC 6803。从逆转录-聚合酶链反应和全基因组DNA微阵列分析的结果表明，稳定的上调基因诱导CO2和HCO 3-摄取系统和rfb簇，编码参与外细胞壁多糖合成的酶。进一步发现了光系统I基因的协调上调，并通过在低C-i（LC）条件下较高的光系统I含量和活性得到支持。细菌型甘油酸途径基因诱导的LC条件下，相反的植物样光呼吸C-2循环的基因。硝酸盐同化基因和令人惊讶的是，也几乎所有的carboxysomal蛋白的下调。然而，对于后者，观察到的Rubisco蛋白大亚基的半衰期延长可能会产生补偿。乙醇酸周转缺陷的突变体（Δ glcD和Δ gcvT）在高C-i条件下显示出一些转录变化，这是野生型细胞中LC条件的特征，如羧基体基因的适度下调。LC条件下的性质与LC野生型相当，包括编码诱导型高亲和力C1摄取系统的基因的强烈响应。电子显微镜显示，在高C-1条件下，突变体Delta glcD中每个细胞的羧基体数量明显增加。这些数据表明，增加水平的光呼吸中间体可能会影响carboxysomal组件，但不干预大多数LC诱导基因的表达。
Concerted changes in the transcriptional pattern and physiological traits that result from long-term (here defined as up to 24 h) limitation of inorganic carbon (C-i) have been investigated for the cyanobacterium Synechocystis sp. strain PCC 6803. Results from reverse transcription-polymerase chain reaction and genome-wide DNA microarray analyses indicated stable up-regulation of genes for inducible CO2 and HCO3- uptake systems and of the rfb cluster that encodes enzymes involved in outer cell wall polysaccharide synthesis. Coordinated up-regulation of photosystem I genes was further found and supported by a higher photosystem I content and activity under low C-i (LC) conditions. Bacterial-type glycerate pathway genes were induced by LC conditions, in contrast to the genes for the plant-like photorespiratory C-2 cycle. Down-regulation was observed for nitrate assimilation genes and surprisingly also for almost all carboxysomal proteins. However, for the latter the observed elongation of the half-life time of the large subunit of Rubisco protein may render compensation. Mutants defective in glycolate turnover (Delta glcD and Delta gcvT) showed some transcriptional changes under high C-i conditions that are characteristic for LC conditions in wild-type cells, like a modest down-regulation of carboxysomal genes. Properties under LC conditions were comparable to LC wild type, including the strong response of genes encoding inducible high-affinity C-i uptake systems. Electron microscopy revealed a conspicuous increase in number of carboxysomes per cell in mutant Delta glcD already under high C-i conditions. These data indicate that an increased level of photorespiratory intermediates may affect carboxysomal components but does not intervene with the expression of majority of LC inducible genes.