Here, we characterized a gene expression system induced by 3-hydroxypropionic acid (3-HP) in Pseudomonas denitrificans. The system consists of a putative LysR-type transcriptional regulator (LTTR) encoded by hpdR and a LTTR-responsive promoter that positively controls the expression of hpdH, encoding 3-HP dehydrogenase in the presence of 3-HP. In the hpdH-responsive promoter region, two operators exhibiting dyad symmetry and designated O₁ and O₂ and centered at the −73 and −30 positions, respectively, were located upstream of the hpdH transcription start site. When either O₁, O₂, or both regions were mutated, the inducibility by the HpdR-3-HP complex was significantly reduced or completely removed, indicating that both sites are required for transcriptional activation. The HpdR protein and its operator sites on hpdH were highly specific for each other, and did not engage in cross-talk with another similar 3-HP-inducible system that is also present in P. denitrificans. This 3-HP-inducible promoter system should be useful in developing biosensors for 3-HP, and/or dynamic gene expression systems for metabolic engineering purposes.

在这里，我们表征了由 3-羟基丙酸 (3-HP) 在反硝化假单胞菌中诱导的基因表达系统。该系统由通过编码一个假定的lysR型转录调节（LTTR）的hpdR和LTTR反应性启动子产生积极控制的表达HPDH，编码3-HP在3-HP的存在脱氢酶。在hpdH 响应启动子区域中，两个具有二元对称性并指定为 O ₁和 O ₂并分别以 -73 和 -30 位置为中心的算子位于hpdH转录起始位点的上游。当 O ₁、O ₂，或者两个区域都发生了突变，HpdR-3-HP 复合物的诱导能力显着降低或完全消除，表明这两个位点都是转录激活所必需的。HpdR 蛋白及其在hpdH上的操作员位点彼此具有高度特异性，并且不会与反硝化假单胞菌中也存在的另一个类似的 3-HP 诱导系统发生串扰。这种 3-HP 诱导型启动子系统可用于开发 3-HP 生物传感器和/或用于代谢工程目的的动态基因表达系统。