Wang Xiaofei, Han Haiyan, Lv Zhihui, Lin Zhiwei, Shang Yongpeng, Xu Tao, Wu Yang, Zhang Ying, Qu Di
Department of Medical Microbiology and Parasitology, Key Laboratory of Medical Molecular Virology of MOE and MOH, School of Basic Medical Sciences, Fudan University, Shanghai, China.
Department of Laboratory Medicine in the Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
J Bacteriol. 2017 Nov 14;199(24). doi: 10.1128/JB.00219-17. Print 2017 Dec 15.
PhoU, a conserved protein that has been proposed to coordinate phosphate import, is a negative regulator of drug tolerance in most bacteria. In , the role of PhoU in biofilm formation and drug tolerance has not yet been investigated. Two PhoU homologs in the genome of have been identified by the presence of the conserved motif E(D)XXXD of PhoU. We separately constructed Δ and Δ mutants of strain 1457. The Δ mutant displayed growth retardation, a weakened biofilm formation capacity, a higher sensitivity to HO, and reduced tolerance to multiple antibiotics. However, deletion of had no effect on those. We compared the transcriptome profiles of the Δ and Δ mutants with that of the parent strain. In the Δ mutant, expression of genes related to inorganic phosphate uptake was significantly upregulated ( operon) and the levels of intracellular inorganic polyphosphate (polyP) were increased. In the Δ mutant, expression of enzymes in the pentose phosphate pathway (PPP) was downregulated and less NADP (NADPH) was detected, consistent with the high sensitivity to HO and the growth retardation of the Δ mutant. The upregulated expression of ATP synthase was consistent with the high intracellular ATP content in the Δ mutant, which may have been related to the lower drug tolerance of the Δ mutant. This study demonstrates that PhoU2, but not PhoU1, in regulates bacterial growth, biofilm formation, oxidative stress, and drug tolerance in association with alterations to inorganic phosphate metabolism, the pentose phosphate pathway, galactose metabolism, the tricarboxylic acid (TCA) or citric cycle, glycolysis and gluconeogenesis, and respiratory reactions. PhoU is widely conserved throughout the bacterial kingdom and plays an important role in response to stress and metabolic maintenance. In our study, two PhoU homologs were found in The function of , but not , in is related to growth, drug tolerance, the oxidative stress response, polyP levels, and ATP accumulation. In addition, regulates biofilm formation. Hence, is a regulator of both drug tolerance and biofilm formation, which are two bacterial properties that present major challenges to the clinical treatment of infections. Analysis of differential gene expression revealed that is involved in fundamental metabolic processes, such as the PPP pathway. These findings indicate that is a crucial regulator in .
PhoU是一种保守蛋白，有人提出它可协调磷酸盐的摄入，在大多数细菌中它是药物耐受性的负调节因子。在[具体研究对象]中，PhoU在生物膜形成和药物耐受性方面的作用尚未得到研究。通过PhoU保守基序E(D)XXXD的存在，在[具体研究对象]的基因组中鉴定出了两个PhoU同源物。我们分别构建了[具体研究对象]菌株1457的Δ[PhoU1基因名称]和Δ[PhoU2基因名称]突变体。Δ[PhoU2基因名称]突变体表现出生长迟缓、生物膜形成能力减弱、对过氧化氢的敏感性增加以及对多种抗生素的耐受性降低。然而，缺失[PhoU1基因名称]对这些方面没有影响。我们将Δ[PhoU1基因名称]和Δ[PhoU2基因名称]突变体的转录组谱与亲本菌株的进行了比较。在Δ[PhoU2基因名称]突变体中，与无机磷酸盐摄取相关的基因表达显著上调（[相关操纵子名称]操纵子），细胞内无机多聚磷酸盐（polyP）水平升高。在Δ[PhoU1基因名称]突变体中，磷酸戊糖途径（PPP）中的酶表达下调，检测到的NADP（NADPH）较少，这与Δ[PhoU1基因名称]突变体对过氧化氢的高敏感性和生长迟缓一致。ATP合酶的上调表达与Δ[PhoU2基因名称]突变体细胞内高ATP含量一致，这可能与Δ[PhoU2基因名称]突变体较低的药物耐受性有关。本研究表明，[具体研究对象]中的PhoU2而非PhoU1通过与无机磷酸盐代谢、磷酸戊糖途径、半乳糖代谢、三羧酸（TCA）或柠檬酸循环、糖酵解和糖异生以及呼吸反应的改变相关联，来调节细菌生长、生物膜形成、氧化应激和药物耐受性。PhoU在整个细菌界广泛保守，在应对压力和维持代谢方面发挥重要作用。在我们的研究中，在[具体研究对象]中发现了两个PhoU同源物。[具体研究对象]中PhoU2而非PhoU1的功能与生长、药物耐受性、氧化应激反应、polyP水平和ATP积累有关。此外，PhoU2调节生物膜形成。因此，PhoU2是药物耐受性和生物膜形成的调节因子，而这两种细菌特性对感染的临床治疗构成了重大挑战。差异基因表达分析表明，PhoU2参与了诸如PPP途径等基本代谢过程。这些发现表明PhoU2在[具体研究对象]中是一个关键调节因子。
