ElyC and Cyclic Enterobacterial Common Antigen Regulate Synthesis of Phosphoglyceride-Linked Enterobacterial Common Antigen.
ElyC and Cyclic Enterobacterial Common Antigen Regulate Synthesis of Phosphoglyceride-Linked Enterobacterial Common Antigen.
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DOI：
10.1128/mbio.02846-21
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发表时间：
2021-12-21
期刊：
影响因子：
6.4
通讯作者：
Mitchell AM
中科院分区：
文献类型：
--
作者：
Rai AK;Carr JF;Bautista DE;Wang W;Mitchell AM
革兰氏阴性细胞被膜是一种复杂的结构，将细胞与其环境区分开来。最近，我们发现肠杆菌共同抗原（ECA）起着维持外膜（OM）通透性屏障的作用，该屏障排斥包括许多抗生素在内的有毒分子。ECA是在整个肠球菌目中发现的保守碳水化合物（例如，沙门氏菌、克雷伯氏菌和耶尔森氏菌）。ECA有两种OM形式（磷酸甘油连接的ECAPG和脂多糖连接的ECALPS）和一种周质形式（环状ECACYC）。在OM的外小叶中发现的ECAPG由通过磷酸二酯键与磷酸甘油酯连接的线性ECA低聚物组成。由聚合的ECA生产ECAPG的方法是未知的。因此，我们着手鉴定在大肠杆菌K-12中利用ECA和肽聚糖生物合成之间的竞争与ECAPG生物合成遗传相互作用的基因。通过转座子定向插入测序，我们确定了elyC和ECAPG生物合成之间的相互作用。ElyC是一种内膜蛋白，先前显示可改变肽聚糖生物合成速率。我们发现Δ elyC在产生ECAPG而没有其他ECA形式的菌株中特异性致死，表明ECAPG生物合成受损或失调。进一步表征表明ElyC以转录后方式抑制ECAPG合成。此外，ElyC对ECA水平的全面影响需要ECACYC的存在。我们的数据表明ECACYC可以调节elyC野生型菌株中ECAPG的合成。总的来说，我们的数据表明ElyC和ECACYC在调节ECAPG产生的新途径中起作用，支持ElyC基于ECACYC的周质水平提供ECAPG产生的反馈调节的模型。
The Gram-negative cell envelope is a complex structure delineating the cell from its environment. Recently, we found that enterobacterial common antigen (ECA) plays a role maintaining the outer membrane (OM) permeability barrier, which excludes toxic molecules including many antibiotics. ECA is a conserved carbohydrate found throughout Enterobacterales (e.g., Salmonella, Klebsiella, and Yersinia). There are two OM forms of ECA (phosphoglyceride-linked ECAPG and lipopolysaccharide-linked ECALPS) and one periplasmic form of ECA (cyclic ECACYC). ECAPG, found in the outer leaflet of the OM, consists of a linear ECA oligomer attached to phosphoglyceride through a phosphodiester linkage. The process through which ECAPG is produced from polymerized ECA is unknown. Therefore, we set out to identify genes interacting genetically with ECAPG biosynthesis in Escherichia coli K-12 using the competition between ECA and peptidoglycan biosynthesis. Through transposon-directed insertion sequencing, we identified an interaction between elyC and ECAPG biosynthesis. ElyC is an inner membrane protein previously shown to alter peptidoglycan biosynthesis rates. We found ΔelyC was lethal specifically in strains producing ECAPG without other ECA forms, suggesting ECAPG biosynthesis impairment or dysregulation. Further characterization suggested ElyC inhibits ECAPG synthesis in a posttranscriptional manner. Moreover, the full impact of ElyC on ECA levels requires the presence of ECACYC. Our data demonstrate ECACYC can regulate ECAPG synthesis in strains wild type for elyC. Overall, our data demonstrate ElyC and ECACYC act in a novel pathway that regulates the production of ECAPG, supporting a model in which ElyC provides feedback regulation of ECAPG production based on the periplasmic levels of ECACYC.