Skagia Aggeliki, Zografou Chrysoula, Venieraki Anastasia, Fasseas Costas, Katinakis Panagiotis, Dimou Maria
Laboratory of General and Agricultural Microbiology, Faculty of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855, Athens, Greece.
Laboratory of Electron Microscopy, Faculty of Crop Science, Agricultural University of Athens, Iera Odos 75, 11855, Athens, Greece.
Genes Cells. 2017 Sep;22(9):810-824. doi: 10.1111/gtc.12514. Epub 2017 Jul 28.
Escherichia coli PpiB is a peptidyl-prolyl cis/trans isomerase (PPIase, EC: 5.2.1.8) with chaperone activity. Here, we show that the ΔppiB deletion strain and the PpiB over-expression wild-type strain are both characterized by defects in cell division involving milder or severe cell filamentation, respectively. Using various PpiB mutants, we show that the PPIase activity of PpiB is necessary for the observed cell filamentation, whereas other structural features apart from the active site are also important for this phenotype. Early divisome components zipA and ftsZ showed decreased expression in ΔppiB cells, whereas the corresponding proteins partially suppressed the division phenotype of ΔppiB cells as well. Although PpiB itself has no obvious specific affinity for the septal ring as a GFP translational fusion showed a diffuse cytoplasmic localization, it interacts with FtsZ employing the C-terminal FtsZ domain, decreases its GTPase activity and when over-expressed shows an inhibitory effect on the proper FtsZ localization at future division sites. Furthermore, additional putative PpiB prey proteins are able to partially restore the ΔppiB phenotype indicating that PpiB is able to control bacterial cell division by probably modulating the function of various other proteins which are indirectly associated with the process.
大肠杆菌PpiB是一种具有伴侣活性的肽基脯氨酰顺反异构酶（PPIase，EC：5.2.1.8）。在此，我们表明ΔppiB缺失菌株和PpiB过表达野生型菌株分别具有细胞分裂缺陷，其特征分别为轻度或严重的细胞丝状化。使用各种PpiB突变体，我们表明PpiB的PPIase活性对于观察到的细胞丝状化是必需的，而除活性位点之外的其他结构特征对于该表型也很重要。早期分裂体成分zipA和ftsZ在ΔppiB细胞中表达降低，而相应的蛋白质也部分抑制了ΔppiB细胞的分裂表型。尽管PpiB本身对隔膜环没有明显的特异性亲和力，因为绿色荧光蛋白（GFP）翻译融合显示出弥漫性的细胞质定位，但它利用FtsZ的C末端结构域与FtsZ相互作用，降低其GTPase活性，并且过表达时对FtsZ在未来分裂位点的正确定位显示出抑制作用。此外，其他推定的PpiB猎物蛋白能够部分恢复ΔppiB表型，这表明PpiB可能通过调节与该过程间接相关的各种其他蛋白质的功能来控制细菌细胞分裂。
