Higo Akiyoshi, Suzuki Takayuki, Ikeuchi Masahiko, Ohmori Masayuki
Department of Life Sciences (Biology), University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.
Department of Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-Ohkubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
Microbiology (Reading). 2007 Nov;153(Pt 11):3685-3694. doi: 10.1099/mic.0.2007/009233-0.
Global transcriptional responses to dehydration and rehydration were determined in Anabaena sp. PCC 7120. Nearly 300 genes were up- or downregulated during both dehydration and rehydration. While as many as 133 genes showed dehydration-specific downregulation, only 29 genes showed dehydration-specific upregulation. In contrast, while only 13 genes showed rehydration-specific downregulation, as many as 259 genes showed rehydration-specific upregulation. The genes upregulated during rehydration responded rapidly and transiently, whereas those upregulated during dehydration did so gradually and persistently. The expression of various genes involved in DNA repair, protein folding and NAD synthesis, as well as genes responding to nitrogen depletion and CO2 limitation, was upregulated during rehydration. Although no genes for transcriptional regulators showed dehydration-specific upregulation, eight showed rehydration-specific upregulation. Among them, two genes, ancrpB and alr0618, encode putative transcriptional activators of the cAMP receptor protein (CRP) family. DNA microarray analysis using gene disruptants revealed that AnCrpB and Alr0618 regulate the genes induced by nitrogen depletion and by CO2 limitation, respectively. We conclude that rehydration is a complex process in which the expression of certain genes, particularly those for metabolism, is dramatically induced.
在鱼腥藻PCC 7120中测定了对脱水和复水的全局转录反应。在脱水和复水过程中，近300个基因被上调或下调。多达133个基因表现出脱水特异性下调，而只有29个基因表现出脱水特异性上调。相反，只有13个基因表现出复水特异性下调，多达259个基因表现出复水特异性上调。复水过程中上调的基因反应迅速且短暂，而脱水过程中上调的基因反应则逐渐且持续。参与DNA修复、蛋白质折叠和NAD合成的各种基因，以及对氮消耗和CO2限制作出反应的基因，在复水过程中表达上调。虽然没有转录调节因子基因表现出脱水特异性上调，但有8个表现出复水特异性上调。其中，两个基因，ancrpB和alr0618，编码假定的cAMP受体蛋白（CRP）家族的转录激活因子。使用基因破坏体的DNA微阵列分析表明，AnCrpB和Alr0618分别调节由氮消耗和CO2限制诱导的基因。我们得出结论，复水是一个复杂的过程，其中某些基因的表达，特别是那些参与代谢的基因，会被显著诱导。
