Escherichia coli SymE is a DNA-binding protein that can condense the nucleoid,Molecular Microbiology

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Escherichia coli SymE is a DNA-binding protein that can condense the nucleoid
Molecular Microbiology ( IF 2.6 ) Pub Date : 2021-12-28 , DOI: 10.1111/mmi.14877
Mary K Thompson ₁ , Isabel Nocedal ₂ , Peter H Culviner ₁ , Tong Zhang ₁ , Kevin R Gozzi ₁ , Michael T Laub _{1,

2}

Affiliation

Type I toxin-antitoxin (TA) systems typically consist of a protein toxin that imbeds in the inner membrane where it can oligomerize and form pores that change membrane permeability, and an RNA antitoxin that interacts directly with toxin mRNA to inhibit its translation. In Escherichia coli, symE/symR is annotated as a type I TA system with a non-canonical toxin. SymE was initially suggested to be an endoribonuclease, but has predicted structural similarity to DNA binding proteins. To better understand SymE function, we used RNA-seq to examine cells ectopically producing it. Although SymE drives major changes in gene expression, we do not find strong evidence of endoribonucleolytic activity. Instead, our biochemical and cell biological studies indicate that SymE binds DNA. We demonstrate that the toxicity of symE overexpression likely stems from its ability to drive severe nucleoid condensation, which disrupts DNA and RNA synthesis and leads to DNA damage, similar to the effects of overproducing the nucleoid-associated protein H-NS. Collectively, our results suggest that SymE represents a new class of nucleoid-associated proteins that is widely distributed in bacteria.

中文翻译：

大肠杆菌 SymE 是一种 DNA 结合蛋白，可以凝聚类核

I 型毒素-抗毒素 (TA) 系统通常由一种嵌入内膜的蛋白质毒素和一种直接与毒素 mRNA 相互作用以抑制其翻译的 RNA 抗毒素组成，前者嵌入内膜，在那里它可以寡聚化并形成改变膜通透性的孔。在大肠杆菌中，symE/symR被注释为具有非规范毒素的 I 型 TA 系统。SymE 最初被认为是一种内切核糖核酸酶，但预测它与 DNA 结合蛋白具有结构相似性。为了更好地理解 SymE 功能，我们使用 RNA-seq 来检查异位产生它的细胞。尽管 SymE 驱动基因表达发生重大变化，但我们没有发现核糖核酸内切活性的有力证据。相反，我们的生化和细胞生物学研究表明 SymE 结合 DNA。我们证明了symE的毒性过度表达可能源于其驱动严重的类核缩合的能力，这会破坏 DNA 和 RNA 的合成并导致 DNA 损伤，类似于类核相关蛋白 H-NS 过量产生的影响。总的来说，我们的结果表明 SymE 代表了一类新的类核相关蛋白，广泛分布于细菌中。

更新日期：2021-12-28

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