Loss of PopZ (At) activity in Agrobacterium tumefaciens by Deletion or Depletion Leads to Multiple Growth Poles, Minicells, and Growth Defects.
Loss of PopZ (At) activity in Agrobacterium tumefaciens by Deletion or Depletion Leads to Multiple Growth Poles, Minicells, and Growth Defects.
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DOI：
10.1128/mbio.01881-17
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发表时间：
2017-11-14
期刊：
影响因子：
6.4
通讯作者：
Zambryski PC
中科院分区：
文献类型：
--
作者：
Grangeon R;Zupan J;Jeon Y;Zambryski PC
根癌农杆菌通过在细菌的一极添加肽聚糖（PG）而生长。在细胞周期中，细胞需要维持两个不同的发育程序，一个在生长极，另一个在惰性的旧极。参与这一过程的蛋白质尚未得到很好的表征。为了进一步表征杆组织蛋白根癌农杆菌PopZ（PopZAt）的作用，我们创建了五个PopZAt结构域的缺失并测定它们的定位。此外，我们创建了popZAt缺失菌株（ΔpopZAt），其表现出具有异位生长极和微细胞的生长和细胞分裂缺陷，但该菌株不稳定。为了克服遗传不稳定性，我们通过用核糖开关替换天然核糖体结合位点来创建诱导型PopZAt菌株。在没有诱导剂茶碱的培养基中培养，细胞看起来像ΔpopZAt细胞，具有分支和小细胞表型。添加茶碱恢复野生型（WT）细胞形状。在耗尽的菌株中的定位实验表明，富含脯氨酸、天冬氨酸和谷氨酸的结构域可能在生长极靶向中起作用。螺旋结构域H3和H4一起也介导极性定位，但仅在WT蛋白存在下，表明H3和H4结构域与WT PopZAt多聚化，以稳定PopZAt的生长极积累。根癌农杆菌是一种杆状细菌，仅在一极添加PG即可生长。在细胞周期中保持细胞不对称性的因素与一个惰性的旧极和一个不断增长的新极还没有很好地理解。在这里，我们调查的作用PopZAt，新月柄杆菌PopZ（PopZCc）的同源物，蛋白质在许多方面的极点的身份在新月柄杆菌必不可少的。我们报告说，PopZAt的损失导致出现分支细胞，微细胞和整体生长缺陷。由于许多植物和动物病原体也采用极性生长，了解根癌农杆菌中的这一过程可能会导致开发新的策略来防止这些病原体的增殖。此外，对根癌农杆菌的研究将为调节细菌极性生长和细胞分裂的遗传网络的进化提供新的见解。
Agrobacterium tumefaciens grows by addition of peptidoglycan (PG) at one pole of the bacterium. During the cell cycle, the cell needs to maintain two different developmental programs, one at the growth pole and another at the inert old pole. Proteins involved in this process are not yet well characterized. To further characterize the role of pole-organizing protein A. tumefaciens PopZ (PopZAt), we created deletions of the five PopZAt domains and assayed their localization. In addition, we created a popZAt deletion strain (ΔpopZAt) that exhibited growth and cell division defects with ectopic growth poles and minicells, but the strain is unstable. To overcome the genetic instability, we created an inducible PopZAt strain by replacing the native ribosome binding site with a riboswitch. Cultivated in a medium without the inducer theophylline, the cells look like ΔpopZAt cells, with a branching and minicell phenotype. Adding theophylline restores the wild-type (WT) cell shape. Localization experiments in the depleted strain showed that the domain enriched in proline, aspartate, and glutamate likely functions in growth pole targeting. Helical domains H3 and H4 together also mediate polar localization, but only in the presence of the WT protein, suggesting that the H3 and H4 domains multimerize with WT PopZAt, to stabilize growth pole accumulation of PopZAt. Agrobacterium tumefaciens is a rod-shaped bacterium that grows by addition of PG at only one pole. The factors involved in maintaining cell asymmetry during the cell cycle with an inert old pole and a growing new pole are not well understood. Here we investigate the role of PopZAt, a homologue of Caulobacter crescentus PopZ (PopZCc), a protein essential in many aspects of pole identity in C. crescentus. We report that the loss of PopZAt leads to the appearance of branching cells, minicells, and overall growth defects. As many plant and animal pathogens also employ polar growth, understanding this process in A. tumefaciens may lead to the development of new strategies to prevent the proliferation of these pathogens. In addition, studies of A. tumefaciens will provide new insights into the evolution of the genetic networks that regulate bacterial polar growth and cell division.