Role of Sigma Factors in Controlling Global Gene Expression in Light/Dark Transitions in the Cyanobacterium Synechocystis sp. Strain PCC 6803
Role of Sigma Factors in Controlling Global Gene Expression in Light/Dark Transitions in the Cyanobacterium Synechocystis sp. Strain PCC 6803
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DOI：
10.1128/jb.01036-07
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发表时间：
2007-08
影响因子：
3.2
通讯作者：
T. Summerfield;L. Sherman
中科院分区：
文献类型：
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作者：
T. Summerfield;L. Sherman
摘要我们报道了蓝细菌集胞藻菌株PCC 6803在野生型、ΔsigB和ΔsigD菌株的光暗转换后的差异基因表达。我们还研究了在葡萄糖存在下日长对ΔsigB ΔsigE突变体的影响。我们的研究结果表明，SigB或SigD的缺失分别在黑暗或光照下主要改变基因表达。在光线中，大约350个基因在ΔsigD菌株中显示出与野生型不同的转录水平，其中超过200个在突变体中上调。在黑暗中，SigB的去除改变了150多个基因，其中136个基因的水平在突变体中比野生型中增加。SigB和SigE两者的去除对混合营养生长条件下的基因表达具有重大影响，并且导致细胞在葡萄糖存在下在8小时光照和16小时黑暗循环下不能生长。我们的结果表明II组σ因子在该生物体转录的整体调节中的重要性，并且通过使用σ循环范式和之前描述的随机释放模型（R. A. Mooney，S. A. Darst和R. Landick，Mol. Cell 20：335-345，2005）。我们将我们的结果与之前计算的光照和黑暗中σ因子的总蛋白质水平相结合（S。Imamura，S. Yoshihara，S.中野、N. Shiozaki，A.山田K.田中，H. Takahashi，M. Asayama和M. Shirai，J. Mol. 325：857-872，2003; S. Imamura，M. Asayama，H.高桥K.田中，H. Takahashi和M. Shirai，FEBS Lett. 554：357-362，2003）。因此，我们得出结论，全局转录的控制是基于存在的各种σ因子的量，并能够结合RNA聚合酶。
ABSTRACT We report on differential gene expression in the cyanobacterium Synechocystis sp. strain PCC 6803 after light-dark transitions in wild-type, ΔsigB, and ΔsigD strains. We also studied the effect of day length in the presence of glucose on a ΔsigB ΔsigE mutant. Our results indicated that the absence of SigB or SigD predominately altered gene expression in the dark or in the light, respectively. In the light, approximately 350 genes displayed transcript levels in the ΔsigD strain that were different from those of the wild type, with over 200 of these up-regulated in the mutant. In the dark, removal of SigB altered more than 150 genes, and the levels of 136 of these were increased in the mutant compared to those in the wild type. The removal of both SigB and SigE had a major impact on gene expression under mixotrophic growth conditions and resulted in the inability of cells to grow in the presence of glucose with 8-h light and 16-h dark cycles. Our results indicated the importance of group II σ factors in the global regulation of transcription in this organism and are best explained by using the σ cycle paradigm with the stochastic release model described previously (R. A. Mooney, S. A. Darst, and R. Landick, Mol. Cell 20:335-345, 2005). We combined our results with the total protein levels of the σ factors in the light and dark as calculated previously (S. Imamura, S. Yoshihara, S. Nakano, N. Shiozaki, A. Yamada, K. Tanaka, H. Takahashi, M. Asayama, and M. Shirai, J. Mol. Biol. 325:857-872, 2003; S. Imamura, M. Asayama, H. Takahashi, K. Tanaka, H. Takahashi, and M. Shirai, FEBS Lett. 554:357-362, 2003). Thus, we concluded that the control of global transcription is based on the amount of the various σ factors present and able to bind RNA polymerase.