Oberto Jacques, Nabti Sabrina, Jooste Valérie, Mignot Hervé, Rouviere-Yaniv Josette
Laboratoire de Physiologie Bactérienne, CNRS, UPR 9073, Institut de Biologie Physico-Chimique, Paris, France.
PLoS One. 2009;4(2):e4367. doi: 10.1371/journal.pone.0004367. Epub 2009 Feb 4.
The Escherichia coli heterodimeric HU protein is a small DNA-bending protein associated with the bacterial nucleoid. It can introduce negative supercoils into closed circular DNA in the presence of topoisomerase I. Cells lacking HU grow very poorly and display many phenotypes.
METHODOLOGY/PRINCIPAL FINDINGS: We analyzed the transcription profile of every Escherichia coli gene in the absence of one or both HU subunits. This genome-wide in silico transcriptomic approach, performed in parallel with in vivo genetic experimentation, defined the HU regulon. This large regulon, which comprises 8% of the genome, is composed of four biologically relevant gene classes whose regulation responds to anaerobiosis, acid stress, high osmolarity, and SOS induction.
CONCLUSIONS/SIGNIFICANCE: The regulation a large number of genes encoding enzymes involved in energy metabolism and catabolism pathways by HU explains the highly pleiotropic phenotype of HU-deficient cells. The uniform chromosomal distribution of the many operons regulated by HU strongly suggests that the transcriptional and nucleoid architectural functions of HU constitute two aspects of a unique protein-DNA interaction mechanism.
大肠杆菌异源二聚体HU蛋白是一种与细菌类核相关的小型DNA弯曲蛋白。在拓扑异构酶I存在的情况下，它能将负超螺旋引入闭环DNA中。缺乏HU的细胞生长非常缓慢，并表现出多种表型。
方法/主要发现：我们分析了在缺失一个或两个HU亚基的情况下，每个大肠杆菌基因的转录谱。这种全基因组的计算机转录组学方法与体内遗传实验并行进行，确定了HU调控子。这个庞大的调控子占基因组的8%，由四个生物学上相关的基因类别组成，其调控对无氧、酸应激、高渗透压和SOS诱导有反应。
结论/意义：HU对大量参与能量代谢和分解代谢途径的酶编码基因的调控解释了HU缺陷细胞的高度多效性表型。由HU调控的许多操纵子在染色体上均匀分布，这强烈表明HU的转录和类核结构功能构成了独特的蛋白质-DNA相互作用机制的两个方面。
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