Kravchenko Uljana, Gogoleva Natalia, Kalubaka Nastassia, Kruk Alla, Diubo Yuliya, Gogolev Yuri, Nikolaichik Yevgeny
Department of Molecular Biology, Belarusian State University, Minsk, Belarus.
Federal Research Center "Kazan Scientific Center of RAS", Kazan Institute of Biochemistry and Biophysics, Kazan, Russia.
Front Microbiol. 2021 Jan 15;11:621391. doi: 10.3389/fmicb.2020.621391. eCollection 2020.
(formerly ) is a recently defined species of soft rot enterobacteria capable of infecting many plant hosts and damaging different tissues. Complex transcriptional regulation of virulence properties can be expected for such a versatile pathogen. However, the relevant information is available only for related species and is rather limited. The PhoPQ two-component system, originally described in pectobacteria as PehRS, was previously shown to regulate a single gene, . Using an insertional mutant of (earlier-), we demonstrate that PhoP regulates at least 115 genes with a majority of them specific for pectobacteria. The functions performed by PhoP-controlled genes include degradation, transport and metabolism of plant-derived carbon sources (polygalacturonate, arabinose-containing polysaccharides and citrate), modification of bacterial cell envelope and stress resistance. We also demonstrated PhoP involvement in establishing the order of plant cell wall decomposition and utilisation of the corresponding breakdown products. Based on experimental data and analysis, we defined a PhoP binding site motif and provided proof for its universality in enteric bacteria. Scanning genome for the locations of this motif suggested a much larger PhoP regulon enriched with the genes important for a plant pathogen, which makes PhoP a global virulence regulator. Potential PhoP targets include many regulatory genes and PhoP control over one of them, , was confirmed experimentally, highlighting the link between the PhoPQ two-component and quorum sensing systems. High concentrations of calcium and magnesium ions were found to abolish the PhoPQ-dependent transcription activation but did not relieve repression. Reduced PhoP expression and minimisation of PhoP dependence of regulon members' expression in cells isolated from potato tuber tissues suggest that PhoPQ system is a key switch of expression levels of multiple virulence-related genes fine-tuned to control the development of -host plant pathosystem.
（以前）是一种最近定义的软腐肠杆菌物种，能够感染许多植物宿主并损害不同组织。对于这样一种多功能病原体，可以预期其毒力特性存在复杂的转录调控。然而，相关信息仅适用于相关物种，且相当有限。PhoPQ双组分系统最初在果胶杆菌中被描述为PehRS，先前已证明它调节单个基因。使用（早期 - ）的插入突变体，我们证明PhoP调节至少115个基因，其中大多数对果胶杆菌具有特异性。PhoP控制的基因执行的功能包括植物衍生碳源（聚半乳糖醛酸、含阿拉伯糖的多糖和柠檬酸盐）的降解、运输和代谢、细菌细胞壁修饰和抗逆性。我们还证明了PhoP参与建立植物细胞壁分解的顺序以及相应分解产物的利用。基于实验数据和分析，我们定义了一个PhoP结合位点基序，并证明了其在肠道细菌中的普遍性。扫描基因组中该基序的位置表明存在一个更大的PhoP调控子，富含对植物病原体重要的基因，这使得PhoP成为一个全局毒力调节因子。潜在的PhoP靶标包括许多调节基因，并且通过实验证实了PhoP对其中一个基因的控制，突出了PhoPQ双组分系统与群体感应系统之间的联系。发现高浓度的钙和镁离子可消除PhoPQ依赖性转录激活，但不能解除抑制作用。从马铃薯块茎组织分离的细胞中PhoP表达降低以及调节子成员表达对PhoP的依赖性最小化，这表明PhoPQ系统是多个毒力相关基因表达水平的关键开关，经过微调以控制 - 宿主植物病理系统的发展。
