Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics, Nanjing, China.
School of Life Sciences, Nanjing Normal University, Nanjing, China.
Front Cell Infect Microbiol. 2018 Mar 20;8:85. doi: 10.3389/fcimb.2018.00085. eCollection 2018.
serotype 2 is an important swine pathogen and an emerging zoonotic agent that causes severe infections. Recent studies have reported a eukaryotic-like Ser/Thr protein kinase (STK) gene and characterized its role in the growth and virulence of different 2 strains. In the present study, phosphoproteomic analysis was adopted to identify substrates of the STK protein. Seven proteins that were annotated to participate in different cell processes were identified as potential substrates, which suggests the pleiotropic effects of on 2 by targeting multiple pathways. Among them, a protein characterized as cell division initiation protein (DivIVA) was further investigated. analysis demonstrated that the recombinant STK protein directly phosphorylates threonine at amino acid position 199 (Thr-199) of DivIVA. This effect could be completely abolished by the T199A mutation. To determine the specific role of DivIVA in growth and division, a mutant was constructed. The Δ strain exhibited impaired growth and division, including lower viability, enlarged cell mass, asymmetrical division caused by aberrant septum, and extremely weak pathogenicity in a mouse infection model. Collectively, our results reveal that STK regulates the cell growth and virulence of 2 by targeting substrates that are involved in different biological pathways. The inactivation of DivIVA leads to severe defects in cell division and strongly attenuates pathogenicity, thereby indicating its potential as a molecular drug target against .
血清型 2 是一种重要的猪病原体和新兴的人畜共患病原体，可引起严重感染。最近的研究报告了一种真核样丝氨酸/苏氨酸蛋白激酶（STK）基因，并描述了其在不同 2 株生长和毒力中的作用。在本研究中，采用磷酸化蛋白质组学分析来鉴定 STK 蛋白的底物。鉴定出 7 种注释为参与不同细胞过程的蛋白质作为潜在的底物，这表明通过靶向多种途径，对 2 具有多效性作用。其中，一种被表征为细胞分裂起始蛋白（DivIVA）的蛋白质进一步被研究。分析表明，重组 STK 蛋白直接磷酸化 DivIVA 氨基酸位置 199 的苏氨酸（Thr-199）。T199A 突变可完全消除这种作用。为了确定 DivIVA 在生长和分裂中的具体作用，构建了一个 突变体。Δ 株表现出生长和分裂受损，包括活力降低、细胞质量增大、由于隔膜异常导致的不对称分裂以及在小鼠感染模型中极低的致病性。总之，我们的结果表明，STK 通过靶向参与不同生物途径的底物来调节 2 的细胞生长和毒力。DivIVA 的失活导致细胞分裂严重缺陷，并强烈减弱致病性，表明其作为针对的分子药物靶点的潜力。
