Rhodopseudomonas palustris CGA009 has two functional ppsR genes, each of which encodes a repressor of photosynthesis gene expression
Rhodopseudomonas palustris CGA009 has two functional ppsR genes, each of which encodes a repressor of photosynthesis gene expression
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DOI：
10.1021/bi061074b
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发表时间：
2006-12-05
期刊：
影响因子：
2.9
通讯作者：
Beatty, J. Thomas
中科院分区：
文献类型：
--
作者：
Braatsch, Stephan;Bernstein, Jeffrey R.;Beatty, J. Thomas
PpsR蛋白是紫色光养细菌中氧化还原依赖性光系统发育的调节剂。与大多数物种不同，沼泽红球藻含有两个ppsR基因。我们发现，每个R. palustris菌株CGA 009 ppsR基因导致在黑暗需氧条件下光系统形成水平升高。两个PpsR突变体的吸收光谱揭示了光捕获峰值振幅增加的定性和定量差异。PpsR 2的螺旋-转角-螺旋DNA结合基序（Arg 439至Cys）在R. palustris菌株CEA 001和CGA 009显示出天然多态性，其不影响蛋白质的阻遏活性。为了评估哪些光合作用基因受两种PpsR蛋白的调控，在微阵列实验中分析了CGA 009和PpsR突变株的转录组谱。大多数但不是所有的光系统基因的转录在突变株中被解阻遏到与体内吸收光谱、峰形和振幅的数学分析、反应中心蛋白水平和所选mRNA的实时PCR一致的水平。在PpsR突变体的转录组分析中被去阻遏的基因的5'端鉴定出紧密间隔的PpsR结合基序重复。这项工作表明，无论是PpsR 1和PpsR 2蛋白从R。palustris菌株CGA 009作为氧响应转录抑制因子发挥作用。
The PpsR protein is a regulator of redox-dependent photosystem development in purple phototrophic bacteria. In contrast to most species, Rhodopseudomonas palustris contains two ppsR genes. We show that the inactivation of each of the R. palustris strain CGA009 ppsR genes results in an elevated level of formation of the photosystem under dark aerobic conditions. Absorption spectra of the two PpsR mutants revealed qualitative and quantitative differences in light-harvesting peak amplitude increases. A sequence difference in the helix-turn-helix DNA binding motif of PpsR2 (Arg 439 to Cys) between R. palustris strains CEA001 and CGA009 is shown to be a natural polymorphism that does not inactivate the repressor activity of the protein. To evaluate which photosynthesis genes are regulated by the two PpsR proteins, transcriptome profiles of the CGA009 and PpsR mutant strains were analyzed in microarray experiments. Transcription of most but not all photosystem genes was derepressed in the mutant strains to levels consistent with the in vivo absorption spectra, mathematical analyses of peak shapes and amplitudes, reaction center protein levels, and real-time PCR of selected mRNAs. Closely spaced PpsR binding motif repeats were identified 5' of genes that were derepressed in the transcriptome analysis of PpsR mutants. This work shows that both the PpsR1 and PpsR2 proteins from R. palustris strain CGA009 function as oxygen-responsive transcriptional repressors.