Translation Stress Positively Regulates MscL-Dependent Excretion of Cytoplasmic Proteins.
Translation Stress Positively Regulates MscL-Dependent Excretion of Cytoplasmic Proteins.
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DOI：
10.1128/mbio.02118-17
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发表时间：
2018-01-30
期刊：
影响因子：
6.4
通讯作者：
Dixon N
中科院分区：
文献类型：
--
作者：
Morra R;Del Carratore F;Muhamadali H;Horga LG;Halliwell S;Goodacre R;Breitling R;Dixon N
细胞质蛋白的明显错误定位或排泄是细菌和真核生物中普遍观察到的现象。然而，关于这种所谓的“非经典蛋白分泌”的机制基础和细胞功能的报道有限。在此，我们报道了重组细胞中蛋白质的过度表达和抗生素诱导的野生型大肠杆菌细胞中的翻译应激都会导致细胞质蛋白(ECP)的排泄。特定条件的代谢和蛋白质组学分析，结合基因敲除，表明大机械敏感通道(MSCL)和替代核糖体救援因子A(ARFA)在ECP中都有作用。总之，这些发现表明，MSCL依赖的蛋白质排泄在渗透胁迫和ArfA介导的翻译应激中都受到正向调节。蛋白质移位是细胞生物体的一个基本特征。像所有单细胞生物体一样，细菌通过专门的分泌途径将蛋白质转移到细胞膜上，从而与环境相互作用。通过特定信号肽的存在，预定要分泌的蛋白质被引导到分泌途径。这项研究表明，在渗透胁迫和翻译胁迫的条件下，大肠杆菌细胞经历了一种排泄现象，即信号肽蛋白通过细胞内外膜转移到细胞外环境中。因此，确认存在可供选择的转位/排泄途径，并了解其功能和调控，对基础微生物学和生物技术非常重要。
The apparent mislocalization or excretion of cytoplasmic proteins is a commonly observed phenomenon in both bacteria and eukaryotes. However, reports on the mechanistic basis and the cellular function of this so-called “nonclassical protein secretion” are limited. Here we report that protein overexpression in recombinant cells and antibiotic-induced translation stress in wild-type Escherichia coli cells both lead to excretion of cytoplasmic protein (ECP). Condition-specific metabolomic and proteomic analyses, combined with genetic knockouts, indicate a role for both the large mechanosensitive channel (MscL) and the alternative ribosome rescue factor A (ArfA) in ECP. Collectively, the findings indicate that MscL-dependent protein excretion is positively regulated in response to both osmotic stress and arfA-mediated translational stress. Protein translocation is an essential feature of cellular organisms. Bacteria, like all single-cell organisms, interact with their environment by translocation of proteins across their cell membranes via dedicated secretion pathways. Proteins destined for secretion are directed toward the secretion pathways by the presence of specific signal peptides. This study demonstrates that under conditions of both osmotic stress and translation stress, E. coli cells undergo an excretion phenomenon whereby signal peptide-less proteins are translocated across both the inner and outer cell membranes into the extracellular environment. Confirming the presence of alternative translocation/excretion pathways and understanding their function and regulation are thus important for fundamental microbiology and biotechnology.