Molecular Biology of Archaea, Max Planck Institute for terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043 Marburg, Germany.
Mol Microbiol. 2013 Apr;88(1):125-39. doi: 10.1111/mmi.12173. Epub 2013 Mar 6.
Linking the motility apparatus to signal transduction systems enables microbes to precisely control their swimming behaviour according to environmental conditions. Bacteria have therefore evolved a complex chemotaxis machinery, which has presumably spread through lateral gene transfer into the euryarchaeal subkingdom. By contrast Crenarchaeota encode no chemotaxis-like proteins but are nevertheless able to connect external stimuli to archaellar derived motility. This raises fundamental questions about the underlying regulatory mechanisms. Recently, we reported that the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius becomes motile upon nutrient starvation by promoting transcription of flaB encoding the filament forming subunits. Here we describe two transcriptional activators as paralogous one-component-systems Saci_1180 and Saci_1171 (ArnR and ArnR1). Deletions of arnR and arnR1 resulted in diminished flaB expression and accordingly the deletion mutants revealed impaired swimming motility. We further identified two inverted repeat sequences located upstream of the flaB core promoter of S. acidocaldarius. These cis-regulatory elements were shown to be critical for ArnR and ArnR1 mediated flaB gene expression in vivo. Finally, bioinformatic analysis revealed ArnR to be conserved not only in Sulfolobales but also in the crenarchaeal order of Desulfurococcales and thus might represent a more general control mechanism of archaeal motility.
将运动器官与信号转导系统连接起来，使微生物能够根据环境条件精确控制其游动行为。因此，细菌进化出了一种复杂的趋化作用机制，这种机制可能通过横向基因转移扩散到广古菌亚界。相比之下，泉古菌门编码的趋化蛋白类似物，但仍然能够将外部刺激与菌毛衍生的运动联系起来。这就提出了关于潜在调控机制的基本问题。最近，我们报道了嗜热嗜酸古菌 Sulfolobus acidocaldarius 在营养饥饿时通过促进编码丝状形成亚基的 flaB 的转录而变得能动。在这里，我们描述了两个转录激活子 Saci_1180 和 Saci_1171（ArnR 和 ArnR1）作为类似的单组分系统的旁系同源物。arnR 和 arnR1 的缺失导致 flaB 表达减少，相应的缺失突变体显示游动运动能力受损。我们进一步鉴定了位于 S. acidocaldarius flaB 核心启动子上游的两个反向重复序列。这些顺式调控元件对于 ArnR 和 ArnR1 在体内介导 flaB 基因表达至关重要。最后，生物信息学分析表明，ArnR 不仅在 Sulfolobales 中保守，而且在泉古菌门的脱硫球菌目中也保守，因此可能代表了一种更普遍的古菌运动控制机制。
