Mikrobiologie und Archaea, Fachbereich Biologie der Technischen Universität Darmstadt, Schnittspahnstrasse 10, D-64287 Darmstadt, Germany.
Microbiology (Reading). 2012 Nov;158(Pt 11):2815-2825. doi: 10.1099/mic.0.060178-0. Epub 2012 Sep 20.
Gas vesicle formation in haloarchaea involves 14 gas vesicle protein (gvp) genes. The strong promoter P(A) drives the expression of gvpACNO, which encodes the major gas vesicle structural proteins GvpA and GvpC, whereas the oppositely oriented promoter P(D) initiates the synthesis of the two regulator proteins, GvpD and GvpE. GvpE activates P(A) and P(D), and requires a 20 nt upstream activator sequence (UAS). UAS(A) and UAS(D) partially overlap in the centre of the 35 bp intergenic region. The basal and GvpE-induced activities of P(A) and P(D) were investigated in Haloferax volcanii transformants. Each UAS consists of two 8 nt portions (P(A), 1A+2A; P(D), 1D+2D), and mutations in the overlapping 1A and 1D portions affected the GvpE induction of both promoters. Substitution of one of the UAS portions by a nonsense sequence showed that a complete UAS is required for activation. The activation of P(A) was more efficient compared with P(D). Promoter P(A) with UAS(A) in configuration 1A+1A was still activated by GvpE, but P(D) was not inducible with UAS(D) in configuration 1D+1D. The TATA box and/or transcription factor B recognition element (BRE) were exchanged between P(A) and P(D). All elements of P(A) functioned well in the environment of 'P(D)' and transferred the stronger P(A) activity to 'P(D)'. In contrast, the respective 'P(A)' chimeras were less active, and BRE(D) was not functional in the environment of 'P(A)'. The relative strengths of the two promoters were substantially determined by the BRE. A 4 nt scanning mutagenesis uncovered an additional regulatory element in the region between TATA(D) and the transcriptional start site of gvpD.
嗜盐古菌中的气泡囊蛋白（Gvp）由 14 个基因编码。强启动子 P(A) 驱动 gvpACNO 的表达，该基因编码主要的气泡囊结构蛋白 GvpA 和 GvpC；而反向的启动子 P(D) 则起始两个调节蛋白 GvpD 和 GvpE 的合成。GvpE 激活 P(A) 和 P(D)，并需要一个 20 个核苷酸的上游激活序列（UAS）。UAS(A) 和 UAS(D) 在 35 个碱基对的基因间区的中心部分部分重叠。在 Haloferax volcanii 转化子中研究了 P(A) 和 P(D) 的基础和 GvpE 诱导活性。每个 UAS 由两个 8 个核苷酸的部分组成（P(A)，1A+2A；P(D)，1D+2D），重叠的 1A 和 1D 部分的突变影响两个启动子的 GvpE 诱导。用无意义序列替代 UAS 部分之一表明，完整的 UAS 是激活所必需的。与 P(D)相比，P(A)的激活效率更高。具有 1A+1A 构型的 UAS(A)的 P(A)仍可被 GvpE 激活，但具有 1D+1D 构型的 UAS(D)的 P(D)不可诱导。TATA 盒和/或转录因子 B 识别元件（BRE）在 P(A)和 P(D)之间交换。P(A)的所有元件在 'P(D)' 的环境中功能良好，并将更强的 P(A)活性转移到 'P(D)'。相比之下，各自的 'P(A)' 嵌合体活性较低，并且 BRE(D)在 'P(A)' 的环境中不起作用。两个启动子的相对强度主要由 BRE 决定。4 个核苷酸扫描诱变在 TATA(D)和 gvpD 转录起始位点之间的区域发现了一个额外的调节元件。
