Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli.
Gene regulation by H-NS as a function of growth conditions depends on chromosomal position in Escherichia coli.
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DOI：
10.1534/g3.114.016139
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发表时间：
2015-02-19
期刊：
影响因子：
--
通讯作者：
Sclavi B
中科院分区：
文献类型：
--
作者：
Brambilla E;Sclavi B
细胞对变化的环境条件的适应需要通过全局调节因子如类核相关蛋白协调调节大量基因的表达。虽然在真核细胞中，基因组位置在基因表达的调控中起着重要作用，但在细菌细胞中，染色体位置是否对这些全局调控因子的效率有影响仍有待确定。在这里，我们第一次表明，基因组位置可以影响由组蛋白样核结构蛋白（H-NS），细菌转录和基因组组织的全球调节调节子调控的启动子的转录活性。我们使用了一种荧光报告蛋白的表达水平作为H-NS活性的局部报告基因，该荧光报告蛋白在基因组沿着的不同位点受H-NS-调节启动子（Phns）的控制。我们的研究结果表明，Phns启动子的活性取决于它是否被放置在富含AT的基因组区域内，这些区域已知优先被H-NS结合。此外，这种基因表达的调节取决于细胞的生长期和生长速率，反映了不同类核蛋白的相对丰度和类核固有的异质组织发生的变化。因此，基因组位置可以在细胞适应环境变化方面发挥重要作用，提供了可以解释进化过程中基因位置选择的适应性优势。
Cellular adaptation to changing environmental conditions requires the coordinated regulation of expression of large sets of genes by global regulatory factors such as nucleoid associated proteins. Although in eukaryotic cells genomic position is known to play an important role in regulation of gene expression, it remains to be established whether in bacterial cells there is an influence of chromosomal position on the efficiency of these global regulators. Here we show for the first time that genome position can affect transcription activity of a promoter regulated by the histone-like nucleoid-structuring protein (H-NS), a global regulator of bacterial transcription and genome organization. We have used as a local reporter of H-NS activity the level of expression of a fluorescent reporter protein under control of an H-NS−regulated promoter (Phns) at different sites along the genome. Our results show that the activity of the Phns promoter depends on whether it is placed within the AT-rich regions of the genome that are known to be bound preferentially by H-NS. This modulation of gene expression moreover depends on the growth phase and the growth rate of the cells, reflecting the changes taking place in the relative abundance of different nucleoid proteins and the inherent heterogeneous organization of the nucleoid. Genomic position can thus play a significant role in the adaptation of the cells to environmental changes, providing a fitness advantage that can explain the selection of a gene’s position during evolution.
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