Robustness of the Process of Nucleoid Exclusion of Protein Aggregates in Escherichia coli
Robustness of the Process of Nucleoid Exclusion of Protein Aggregates in Escherichia coli
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DOI：
10.1128/jb.00848-15
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发表时间：
2016-03-01
影响因子：
3.2
通讯作者：
Ribeiro, Andre S.
中科院分区：
文献类型：
--
作者：
Neeli-Venkata, Ramakanth;Martikainen, Antti;Ribeiro, Andre S.
大肠杆菌通过类核排斥将蛋白质聚集体分离到两极。与细胞分裂相结合，这在随后的细胞世代中产生异质聚集体分布。我们研究了这个过程的鲁棒性与不同的介质丰富度和抗生素的压力，这会影响类核的大小，使用多模式，延时显微镜活细胞表达荧光标记的伴侣（IbpA），它确定在体内的聚集体的位置，和HupA-mCherry，一个荧光变体的核相关蛋白。我们发现，类核的长轴和短轴的相对大小变化很大，以正相关的方式，与中等丰富度和抗生素应力。聚集体的分布沿着的主要细胞轴之间的条件和协议的类核排斥现象也发生变化。因此，在细胞分裂之前在中细胞区域的聚集体的分数在条件之间不同，这将影响后代细胞之间聚集体分配的不对称程度。最后，从聚集体位移分布，类核相对大小和时空聚集体分布的各向异性的峰值的位置，我们发现，从中间细胞的可检测的聚集体的排除是最明显的中等大小的类核，这是最常见的最佳条件下的细胞。我们的结论是，E。大肠杆菌是显着强大的，但不能免疫的压力，由于有形的影响，这些对nucleoid大小。重要大肠杆菌分离蛋白质聚集体的两极，通过nucleoid排斥。从活的单细胞显微镜研究的鲁棒性，这个过程中的各种应力已知影响类核的大小，我们发现，类核的大小和聚集体的优先位置变化之间的条件一致。此外，类核对聚集体定位的影响程度在不同条件下不同，导致中间细胞的聚集体数量在细胞分裂事件中不同，这将影响后代细胞之间聚集体分配的不对称程度。最后，我们发现，聚集隔离的细胞两极是最明显的细胞与中型核。我们的结论是，无能量的过程中的中间细胞排斥的聚集体部分失去了有效性，在压力条件下。
Escherichia coli segregates protein aggregates to the poles by nucleoid exclusion. Combined with cell divisions, this generates heterogeneous aggregate distributions in subsequent cell generations. We studied the robustness of this process with differing medium richness and antibiotics stress, which affect nucleoid size, using multimodal, time-lapse microscopy of live cells expressing both a fluorescently tagged chaperone (IbpA), which identifies in vivo the location of aggregates, and HupA-mCherry, a fluorescent variant of a nucleoid-associated protein. We find that the relative sizes of the nucleoid's major and minor axes change widely, in a positively correlated fashion, with medium richness and antibiotic stress. The aggregate's distribution along the major cell axis also changes between conditions and in agreement with the nucleoid exclusion phenomenon. Consequently, the fraction of aggregates at the midcell region prior to cell division differs between conditions, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, from the location of the peak of anisotropy in the aggregate displacement distribution, the nucleoid relative size, and the spatiotemporal aggregate distribution, we find that the exclusion of detectable aggregates from midcell is most pronounced in cells with mid-sized nucleoids, which are most common under optimal conditions. We conclude that the aggregate management mechanisms of E. coli are significantly robust but are not immune to stresses due to the tangible effect that these have on nucleoid size.IMPORTANCEEscherichia coli segregates protein aggregates to the poles by nucleoid exclusion. From live single-cell microscopy studies of the robustness of this process to various stresses known to affect nucleoid size, we find that nucleoid size and aggregate preferential locations change concordantly between conditions. Also, the degree of influence of the nucleoid on aggregate positioning differs between conditions, causing aggregate numbers at midcell to differ in cell division events, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, we find that aggregate segregation to the cell poles is most pronounced in cells with mid-sized nucleoids. We conclude that the energy-free process of the midcell exclusion of aggregates partially loses effectiveness under stressful conditions.