TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin 300457, China.
Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Nankai University, Tianjin 300457, China.
Int J Mol Sci. 2023 Sep 23;24(19):14473. doi: 10.3390/ijms241914473.
The pyruvate dehydrogenase complex regulator (PdhR) was originally identified as a repressor of the operon, which encodes the pyruvate dehydrogenase complex (PDHc) and PdhR itself. According to previous reports, PdhR plays a regulatory role in the physiological and metabolic pathways of bacteria. At present, the function of PdhR in is still poorly understood. In this study, RNA sequencing (RNA-Seq) of the wild-type strain and the Δ mutant strains was performed for comparison to identify the PdhR-controlled pathways, revealing that PdhR regulates ~7.38% of the transcriptome. We found that the deletion of resulted in the downregulation of practically all polar and lateral flagella genes in ; meanwhile, motility assay and transmission electron microscopy (TEM) confirmed that the Δ mutant was non-motile and lacked flagella. Moreover, the results of RNA-seq and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) showed that PdhR positively regulated the expression of the T3SS cluster, and the Δ mutant significantly reduced the ability of to infect Caco-2 cells compared with the WT. Consistent with previous research, pyruvate-sensing PdhR directly binds to its promoter and inhibits -- operon expression. In addition, we identified two additional downstream genes, and , that are directly negatively regulated by PdhR. Furthermore, we also demonstrated that ArcA was identified as being located upstream of and and directly negatively regulating their expression. Overall, we revealed the function and regulatory pathway of PdhR, which will allow for a more in-depth investigation into pathogenicity as well as the complex regulatory network.
丙酮酸脱氢酶复合体调节因子（PdhR）最初被鉴定为操纵子的阻遏物，该操纵子编码丙酮酸脱氢酶复合体（PDHc）和 PdhR 本身。根据以前的报告，PdhR 在细菌的生理和代谢途径中发挥调节作用。目前，PdhR 在 中的功能仍知之甚少。在这项研究中，对野生型菌株和 Δ 突变株进行了 RNA 测序（RNA-Seq）比较，以鉴定 PdhR 控制的途径，结果表明 PdhR 调节约 7.38%的 转录组。我们发现 缺失导致 中几乎所有极性和侧向鞭毛基因的下调；同时，运动性测定和透射电子显微镜（TEM）证实 Δ 突变体是非运动性的，并且缺乏鞭毛。此外，RNA-seq 和定量实时聚合酶链反应（qRT-PCR）的结果表明，PdhR 正向调节 T3SS 簇的表达，与 WT 相比，Δ 突变体显着降低了 感染 Caco-2 细胞的能力。与以前的研究一致，丙酮酸感应的 PdhR 直接结合到其启动子上并抑制 -- 操纵子表达。此外，我们还鉴定了两个直接受 PdhR 负调控的另外两个下游基因 和 。此外，我们还证明 ArcA 被鉴定为位于 和 上游，并直接负调控它们的表达。总体而言，我们揭示了 PdhR 的功能和调节途径，这将允许更深入地研究 致病性以及复杂的调节网络。
