Napoli A, van der Oost J, Sensen C W, Charlebois R L, Rossi M, Ciaramella M
Institute of Protein Biochemistry and Enzymology, Consiglio Nazionale delle Ricerche, 80125 Naples, Italy.
J Bacteriol. 1999 Mar;181(5):1474-80. doi: 10.1128/JB.181.5.1474-1480.1999.
Regulation of gene expression in the domain Archaea, and specifically hyperthermophiles, has been poorly investigated so far. Biochemical experiments and genome sequencing have shown that, despite the prokaryotic cell and genome organization, basal transcriptional elements of members of the domain Archaea (i.e., TATA box-like sequences, RNA polymerase, and transcription factors TBP, TFIIB, and TFIIS) are of the eukaryotic type. However, open reading frames potentially coding for bacterium-type transcription regulation factors have been recognized in different archaeal strains. This finding raises the question of how bacterial and eukaryotic elements interact in regulating gene expression in Archaea. We have identified a gene coding for a bacterium-type transcription factor in the hyperthermophilic archaeon Sulfolobus solfataricus. The protein, named Lrs14, contains a potential helix-turn-helix motif and is related to the Lrp-AsnC family of regulators of gene expression in the class Bacteria. We show that Lrs14, expressed in Escherichia coli, is a highly thermostable DNA-binding protein. Bandshift and DNase I footprint analyses show that Lrs14 specifically binds to multiple sequences in its own promoter and that the region of binding overlaps the TATA box, suggesting that, like the E. coli Lrp, Lrs14 is autoregulated. We also show that the lrs14 transcript is accumulated in the late growth stages of S. solfataricus.
到目前为止,古菌域,特别是嗜热古菌中的基因表达调控研究得还很少。生化实验和基因组测序表明,尽管古菌域成员具有原核细胞和基因组结构,但其基础转录元件(即类TATA盒序列、RNA聚合酶以及转录因子TBP、TFIIB和TFIIS)却是真核类型的。然而,在不同的古菌菌株中已经识别出了可能编码细菌型转录调控因子的开放阅读框。这一发现引发了一个问题,即细菌和真核元件在古菌基因表达调控中是如何相互作用的。我们在嗜热古菌嗜热栖热菌中鉴定出了一个编码细菌型转录因子的基因。该蛋白名为Lrs14,含有一个潜在的螺旋-转角-螺旋基序,并且与细菌类中基因表达调控的Lrp-AsnC家族相关。我们发现,在大肠杆菌中表达的Lrs14是一种高度耐热的DNA结合蛋白。凝胶迁移和DNase I足迹分析表明,Lrs14特异性结合其自身启动子中的多个序列,并且结合区域与TATA盒重叠,这表明,与大肠杆菌的Lrp一样,Lrs14是自我调控的。我们还表明,lrs14转录本在嗜热栖热菌的生长后期积累。