Structure of a novel antibacterial toxin that exploits elongation factor Tu to cleave specific transfer RNAs [electronic resource]

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Ngôn ngữ: eng

Ký hiệu phân loại: 572.6 Proteins

Thông tin xuất bản: Bethesda, Md. : Oak Ridge, Tenn. : National Institutes of Health (U.S.) ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2017

Mô tả vật lý: Size: p. 10306-10320 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 260404

 Contact-dependent growth inhibition (CDI) is a mechanism of inter-cellular competition in which Gram-negative bacteria exchange polymorphic toxins using type V secretion systems. Here, we present structures of the CDI toxin from <
 i>
 Escherichia coli<
 /i>
  NC101 in ternary complex with its cognate immunity protein and elongation factor Tu (EF-Tu). The toxin binds exclusively to domain 2 of EF-Tu, partially overlapping the site that interacts with the 3'-end of aminoacyl-tRNA (aa-tRNA). The toxin exerts a unique ribonuclease activity that cleaves the single-stranded 3'-end from tRNAs that contain guanine discriminator nucleotides. EF-Tu is required to support this tRNase activity <
 i>
 in vitro<
 /i>
 , suggesting the toxin specifically cleaves substrate in the context of GTP�EF-Tu�aa-tRNA complexes. However, superimposition of the toxin domain onto previously solved GTP�EF-Tu�aa-tRNA structures reveals potential steric clashes with both aa-tRNA and the switch I region of EF-Tu. Further, the toxin induces conformational changes in EF-Tu, displacing a ?-hairpin loop that forms a critical salt-bridge contact with the 3'-terminal adenylate of aa-tRNA. Altogether, these observations suggest that the toxin remodels GTP�EF-Tu�aa-tRNA complexes to free the 3'-end of aa-tRNA for entry into the nuclease active site.
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