A Spontaneous rapZ Mutant Impairs Infectivity of Lytic Bacteriophage vB EcoM JS09 against Enterotoxigenic Escherichia coli

文献类型： 外文期刊

第一作者： Zhou, Yan

作者： Zhou, Yan;Bao, Hongduo;Zhang, Hui;Pang, Maoda;Zhu, Shujiao;Wang, Ran

作者机构：

关键词： rapZ; lytic bacteriophage; phage resistance; infectivity; enterotoxigenic E. coli; LPS; glmS

期刊名称：MSPHERE （ 影响因子：4.282； 五年影响因子：4.466 ）

ISSN： 2379-5042

年卷期： 2021 年 6 卷 2 期

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收录情况： SCI

摘要： Our understanding of the mechanisms underlying phage-bacterium interactions remains limited. In Escherichia coli, RapZ regulates glucosamine-6-phosphate (GlcN6P) metabolism, the formation of which initiates synthesis of the bacterial cell envelope, including lipopolysaccharides (LPS). However, the role of RapZ, if any, on phage infectivity remains to be investigated. Here, we isolated strains of enterotoxigenic E. coli (ETEC) resistant to its specific lytic bacteriophage vB_EcoM _JS09 (JS09) in a phage aerosol spray experiment. Whole-genome analysis of phage-resistant bacteria revealed the rapZ gene acquired a premature stop mutation at amino acid 227. Here, we report that the mutation in the rapZ gene confers resistance by inhibiting 93.5% phage adsorption. Furthermore, this mutation changes the morphology of phage plaques, reduces efficiency of plating and phage propagation efficiency, and impairs the infectivity of phage JS09 against ETEC. Using scanning electron microscopy assays, we attribute the inability of the phage to adsorb to the loss of receptors in strains with defective RapZ. Analysis of the LPS profile shows that strains with defective RapZ inhibit phage infection by changing the LPS profile in E. coli. Preincubation of phage JS09 with LPS extracted from a wild-type (WT) strain blocked infection, suggesting LPS is the host receptor for phage J509 adsorption. Our data uncover the mechanism by which ETEC resists infection of phage JS09 by mutating the ropZ gene and then increasing the expression of glmS and changing the phage receptor-LPS profile. These findings provide insight into the function of the rapZ gene for efficient infection of phage J609. IMPORTANCE The development of phage-resistant bacteria is a challenging problem for phage therapy. However, our knowledge of phage resistance mechanisms is still limited. RapZ is an RNase adaptor protein encoded by the rapZ gene and plays an important function in Gram-positive and Gram-negative bacteria. Here, we report the whole-genome analysis of a phage-resistant enterotoxigenic Escherichia coli (ETEC) strain, which revealed that the rapZ gene acquired a premature stop mutation (E227Stop). We show that the premature stop mutation of rapZ impairs the infectivity of phage JS09 in ETEC. Furthermore, our findings indicate that ETEC becomes resistant against the adsorption and infection of phage JS09 by mutating the rapZ gene, increasing the expression of glmS, and changing the phage receptor-LPS profile. It is also first reported here that RapZ is essential for efficient infection of phage JS09.

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