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An engineered ClyA nanopore detects folded target proteins by selective external association and pore entry.

ABSTRACT: Nanopores have been used in label-free single-molecule studies, including investigations of chemical reactions, nucleic acid analysis, and applications in sensing. Biological nanopores generally perform better than artificial nanopores as sensors, but they have disadvantages including a fixed diameter. Here we introduce a biological nanopore ClyA that is wide enough to sample and distinguish large analyte proteins, which enter the pore lumen. Remarkably, human and bovine thrombins, despite 86% sequence identity, elicit characteristic ionic current blockades, which at -50 mV differ in their main current levels by 26 ± 1 pA. The use of DNA aptamers or hirudin as ligands further distinguished the protein analytes. Finally, we constructed ClyA nanopores decorated with covalently attached aptamers. These nanopores selectively captured and internalized cognate protein analytes but excluded noncognate analytes, in a process that resembles transport by nuclear pores.

SUBMITTER: Soskine M

PROVIDER: S-EPMC3440510 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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An engineered ClyA nanopore detects folded target proteins by selective external association and pore entry.

Soskine Misha M Biesemans Annemie A Moeyaert Benjamien B Cheley Stephen S Bayley Hagan H Maglia Giovanni G

Nano letters 20120806 9

Nanopores have been used in label-free single-molecule studies, including investigations of chemical reactions, nucleic acid analysis, and applications in sensing. Biological nanopores generally perform better than artificial nanopores as sensors, but they have disadvantages including a fixed diameter. Here we introduce a biological nanopore ClyA that is wide enough to sample and distinguish large analyte proteins, which enter the pore lumen. Remarkably, human and bovine thrombins, despite 86% s ...[more]

PMID: 22849517

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Project description:Engineered Salmonella typhimurium (S.t-ΔpGlux/pT-ClyA) and attenuated Salmonella typhimurium (SL: Salmonella typhimurium with a defect in the synthesis of guanine 5'-diphosphate-3'-diphosphate) exhibit similar tumor targeting capabilities (Kim et al. in Theranostics 5:1328-1342, 2015; Jiang et al. in Mol Ther 18:635-642, 2013), but S.t-ΔpGlux/pT-ClyA exerts superior tumor suppressive effects. The aim of this study was to investigate whether S.t-ΔpGlux/pT-ClyA inhibits colon cancer growth and recurrence by promoting increased IL-1β production. The CT26 tumor mouse model was used, and mice were treated in the following ways: PBS, S.t-ΔpGlux/pT-ClyA(+) + IL-1βAb, SL, S.t-ΔpGlux/pT-ClyA(-), and S.t-ΔpGlux/pT-ClyA(+). Dynamic evaluation of the efficacy of S.t-ΔpGlux/pT-ClyA in the treatment of colon cancer was assessed by MRI. Western blot, immunofluorescence and flow cytometry analysis were used to investigate IL-1β-derived cells and IL-1β expression on tumor cells and immune cells to analyze the regulatory mechanism. IL-1β levels in tumors colonized by S.t-ΔpGlux/pT-ClyA were significantly increased and maintained at high levels compared to control treatments. This increase caused tumors to subside without recurrence. We examined the immune cells mediating S.t-ΔpGlux/pT-ClyA-induced tumor suppression and examined the major cell types producing IL-1β. We found that macrophages and dendritic cells were the primary IL-1β producers. Inhibition of IL-1β in mice treated with S.t-ΔpGlux/pT-ClyA using an IL-1β antibody caused tumor growth to resume. This suggests that IL-1β plays an important role in the treatment of cancer by S.t-ΔpGlux/pT-ClyA. We found that in St-ΔpGlux/pT-ClyA-treated tumors, expression of molecules involved in signaling pathways, such as NLRP3, ASC, Caspase1, TLR4, MyD88, NF-kB and IL-1β, were upregulated, while in ΔppGpp S. typhimurium treated animals, TLR4, MyD88, NF-kB and IL-1β were upregulated with NLRP3, ASC, and Caspase1 being rarely expressed or not expressed at all. Using S.t-ΔpGlux/pT-ClyA may simultaneously activate TLR4 and NLRP3 signaling pathways, which increase IL-1β expression and enhance inhibition of colon cancer growth without tumor recurrence. This study provides a novel platform for treating colon cancer.

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An engineered ClyA nanopore detects folded target proteins by selective external association and pore entry.

Publications

An engineered ClyA nanopore detects folded target proteins by selective external association and pore entry.

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