Espinosa Elena, Daniel Sandra, Hernández Sara B, Goudin Anthony, Cava Felipe, Barre François-Xavier, Galli Elisa
Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France.
The laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umeå, Sweden.
Appl Environ Microbiol. 2021 Mar 1;87(5). doi: 10.1128/AEM.02305-20. Epub 2020 Dec 18.
, the agent of the deadly human disease cholera, propagates as a curved rod-shaped bacterium in warm waters. It is sensitive to cold, but persists in cold waters under the form of viable but non-dividing coccoidal shaped cells. Additionally, is able to form non-proliferating spherical cells in response to cell wall damage. It was recently reported that L-arabinose, a component of the hemicellulose and pectin of terrestrial plants, stops the growth of Here, we show that L-arabinose induces the formation of spheroplasts that lose the ability to divide and stop growing in volume over time. However, they remain viable and upon removal of L-arabinose they start expanding in volume, form branched structures and give rise to cells with a normal morphology after a few divisions. We further show that WigKR, a histidine kinase/response regulator pair implicated in the induction of a high expression of cell wall synthetic genes, prevents the lysis of the spheroplasts during growth restart. Finally, we show that the physiological perturbations result from the import and catabolic processing of L-arabinose by the homolog of the galactose transport and catabolic system. Taken together, our results suggest that the formation of non-growing spherical cells is a common response of exposed to detrimental conditions. They also permit to define conditions preventing any physiological perturbation of when using L-arabinose to induce gene expression from the tightly regulated promoter of the operon. among other bacteria form transient cell wall deficient forms as a response to different stresses and revert to proliferating rods when permissive conditions have been restored. Such cellular forms have been associated to antimicrobial tolerance, chronic infections and environmental dispersion.The effect of L-Ara on could provide an easily tractable model to study the ability of to form viable reversible spheroplasts. Indeed, the quick transition to spheroplasts and reversion to proliferating rods by addition or removal of L-Ara is ideal to understand the genetic program governing this physiological state and the spatial rearrangements of the cellular machineries during cell shape transitions.
霍乱弧菌是致命人类疾病霍乱的病原体，在温暖水域中以弯曲杆状细菌的形式繁殖。它对寒冷敏感，但能以有活力但不分裂的球状细胞形式在冷水中存活。此外，霍乱弧菌能够因细胞壁损伤而形成不增殖的球形细胞。最近有报道称，陆地植物半纤维素和果胶的成分L-阿拉伯糖能阻止霍乱弧菌的生长。在此，我们表明L-阿拉伯糖诱导形成原生质球，这些原生质球失去分裂能力并随着时间推移停止体积增长。然而，它们仍保持活力，去除L-阿拉伯糖后，它们开始体积膨胀，形成分支结构，并在几次分裂后产生形态正常的细胞。我们进一步表明，WigKR是一对参与诱导细胞壁合成基因高表达的组氨酸激酶/应答调节因子，可防止原生质球在生长重启期间裂解。最后，我们表明生理扰动是由霍乱弧菌中与大肠杆菌半乳糖转运和分解代谢系统同源的系统对L-阿拉伯糖的导入和分解代谢过程引起的。综上所述，我们的结果表明，不生长的球形细胞的形成是霍乱弧菌暴露于有害条件下的常见反应。它们还允许确定在使用L-阿拉伯糖从霍乱弧菌操纵子的严格调控启动子诱导基因表达时防止霍乱弧菌任何生理扰动的条件。霍乱弧菌等其他细菌会形成短暂的细胞壁缺陷形式以应对不同压力，并在允许条件恢复时恢复为增殖杆状。这种细胞形式与抗菌耐受性、慢性感染和环境扩散有关。L-阿拉伯糖对霍乱弧菌的作用可以提供一个易于处理的模型来研究霍乱弧菌形成有活力的可逆原生质球的能力。事实上，通过添加或去除L-阿拉伯糖快速转变为原生质球并恢复为增殖杆状，对于理解控制这种生理状态的遗传程序以及细胞形状转变期间细胞机器的空间重排是理想的。
