Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan.
Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
Proc Natl Acad Sci U S A. 2017 Sep 19;114(38):E8025-E8034. doi: 10.1073/pnas.1703731114. Epub 2017 Sep 5.
RNase E is an essential enzyme that forms multicomponent ribonucleolytic complexes known as "RNA degradosomes." These complexes consist of four major components: RNase E, PNPase, RhlB RNA helicase, and enolase. However, the role of enolase in the RNase E/degradosome is not understood. Here, we report that presence of enolase in the RNase E/degradosome under anaerobic conditions regulates cell morphology, resulting in MG1655 cell filamentation. Under anaerobic conditions, enolase bound to the RNase E/degradosome stabilizes the small RNA (sRNA) DicF, i.e., the inhibitor of the cell division gene , through chaperon protein Hfq-dependent regulation. RNase E/enolase distribution changes from membrane-associated patterns under aerobic to diffuse patterns under anaerobic conditions. When the enolase-RNase E/degradosome interaction is disrupted, the anaerobically induced characteristics disappear. We provide a mechanism by which uses enolase-bound degradosomes to switch from rod-shaped to filamentous form in response to anaerobiosis by regulating RNase E subcellular distribution, RNase E enzymatic activity, and the stability of the sRNA DicF required for the filamentous transition. In contrast to nonpathogenic strains, pathogenic strains predominantly have multiple copies of sRNA DicF in their genomes, with cell filamentation previously being linked to bacterial pathogenesis. Our data suggest a mechanism for bacterial cell filamentation during infection under anaerobic conditions.
RNase E 是一种必需的酶，它形成称为“RNA 降解体”的多成分核糖核酸酶复合物。这些复合物由四个主要成分组成：RNase E、PNPase、RhlB RNA 解旋酶和烯醇酶。然而，烯醇酶在 RNase E/降解体中的作用尚不清楚。在这里，我们报告在厌氧条件下，烯醇酶存在于 RNase E/降解体中调节细胞形态，导致 MG1655 细胞丝状化。在厌氧条件下，烯醇酶与 RNase E/降解体结合通过 chaperon 蛋白 Hfq 依赖性调节稳定小 RNA（sRNA） DicF，即细胞分裂基因的抑制剂。RNase E/烯醇酶的分布从有氧条件下的膜相关模式变为厌氧条件下的弥散模式。当烯醇酶-RNase E/降解体相互作用被破坏时，厌氧诱导的特征消失。我们提供了一种机制，即通过调节 RNase E 亚细胞分布、RNase E 酶活性和丝状转变所需的 sRNA DicF 的稳定性，利用烯醇酶结合的降解体使从杆状到丝状的转变，从而使 对缺氧的反应从杆状到丝状。与非致病性菌株不同，致病性 菌株的基因组中通常有多个 sRNA DicF 拷贝，细胞丝状化以前与细菌发病机制有关。我们的数据表明了在厌氧条件下感染过程中细菌细胞丝状化的一种机制。
