The absence of osmoregulated periplasmic glucan confers antimicrobial resistance and increases virulence in Escherichia coli
The absence of osmoregulated periplasmic glucan confers antimicrobial resistance and increases virulence in Escherichia coli
复制标题
缺乏渗透调节的周质葡聚糖会导致大肠杆菌产生耐药性并增加毒力
DOI：
10.1128/jb.00515-20
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kaito C.
中科院分区：
文献类型：
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作者：
Murakami K;Nasu H;Fujiwara T;Takatsu N;Yoshida N;Furuta K;Kaito C.
阐明细菌获得毒力特性的分子机制对于了解细菌毒力系统具有重要意义。在本研究中，我们在家蚕感染模型中使用了细菌进化方法，发现编码渗透调节周质葡聚糖(OPG)合成酶的theopgGH操纵子的缺失增加了非致病实验室菌株对家蚕的毒力。该基因敲除突变体对宿主抗菌肽和抗生素表现出抗性。与亲本菌株相比，opgGH基因敲除突变株产生了更多的可乐酸，这与大肠杆菌对抗生素的耐药性有关。RNA序列分析表明，该基因敲除改变了多种基因的表达，包括在抗生素耐药性中起作用的evgS/evg两组分系统。在可乐酸阴性背景和anevgS-空背景下，opgGH型基因敲除均增强了大肠杆菌对抗生素的抗性，并增强了大肠杆菌的杀蚕活性。在与opgGH基因相互作用的envZ/ompR双组分系统的零背景下，opgGH基因敲除家蚕提高了家蚕的抗药性和毒力。这些发现表明，OPG的缺乏以一种不依赖于结肠癌、evgS/EVGA-和envZ/ompR的方式在大肠杆菌中赋予了抗菌素耐药性和毒力。重要的是，增加大肠杆菌毒力的基因突变类型尚不清楚，部分原因是可用于分离毒力增强的细菌突变株的方法有限。在家蚕感染模型中，我们采用了细菌进化的方法，用诱变细菌感染家蚕，并从死亡家蚕中分离出高毒力的细菌突变株。我们发现，OPG合成酶的敲除增加了大肠杆菌对家蚕的毒力。OPG基因敲除突变株对宿主抗菌肽和抗生素均具有抗药性。我们的发现不仅表明了一种在大肠杆菌中获得毒力的新机制，而且支持了细菌实验进化方法在家蚕感染模型中的有效性。
Clarifying the molecular mechanisms by which bacteria acquire virulence traits is important for understanding the bacterial virulence system. In the present study, we utilized a bacterial evolution method in a silkworm infection model and revealed that deletion of theopgGHoperon, encoding synthases for osmoregulated periplasmic glucan (OPG), increased the virulence of a nonpathogenic laboratory strain of Escherichia coli against silkworms. TheopgGHknockout mutant exhibited resistance to host antimicrobial peptides and antibiotics. Compared with the parent strain, theopgGHknockout mutant produced greater amounts of colanic acid, which is involved in E. coli resistance to antibiotics. RNA sequence analysis revealed that theopgGHknockout altered the expression of various genes, including theevgS/evgAtwo-component system that functions in antibiotic resistance. In both a colanic acid-negative background and anevgS-null background, theopgGHknockout increased E. coli resistance to antibiotics and increased the silkworm-killing activity of E. coli. In the null background of theenvZ/ompRtwo-component system, which genetically interacts withopgGH, theopgGHknockout increased antibiotic resistance and virulence in silkworms. These findings suggest that the absence of OPG confers antimicrobial resistance and virulence in E. coli in a colanic acid-,evgS/evgA-, andenvZ/ompR-independent manner.IMPORTANCEThe gene mutation types that increase the bacterial virulence of Escherichia coli remain unclear, in part due to the limited number of methods available for isolating bacterial mutants with increased virulence. We utilized a bacterial evolution method in the silkworm infection model, in which silkworms were infected with mutagenized bacteria and highly virulent bacterial mutants were isolated from dead silkworms. We revealed that knockout of OPG synthases increased E. coli virulence against silkworms. The OPG knockout mutants were resistant to host antimicrobial peptides as well as antibiotics. Our findings not only suggest a novel mechanism for virulence acquisition in E. coli but also support the usefulness of the bacterial experimental evolution method in the silkworm infection model.