{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T02:53:32Z","timestamp":1779245612595,"version":"3.51.4"},"reference-count":63,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2023,6,9]],"date-time":"2023-06-09T00:00:00Z","timestamp":1686268800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"German Research Foundation (DFG)","award":["316249678\u2014SFB 1279"],"award-info":[{"award-number":["316249678\u2014SFB 1279"]}]},{"name":"German Research Foundation (DFG)","award":["251293561\u2014SFB 1149"],"award-info":[{"award-number":["251293561\u2014SFB 1149"]}]},{"name":"German Research Foundation (DFG)","award":["316249678\u2014SFB 1279"],"award-info":[{"award-number":["316249678\u2014SFB 1279"]}]},{"name":"German Research Foundation (DFG)","award":["251293561\u2014SFB 1149"],"award-info":[{"award-number":["251293561\u2014SFB 1149"]}]},{"name":"Medical Faculty Ulm","award":["316249678\u2014SFB 1279"],"award-info":[{"award-number":["316249678\u2014SFB 1279"]}]},{"name":"Medical Faculty Ulm","award":["251293561\u2014SFB 1149"],"award-info":[{"award-number":["251293561\u2014SFB 1149"]}]},{"name":"International Graduate School in Molecular Medicine Ulm (IGradU)","award":["316249678\u2014SFB 1279"],"award-info":[{"award-number":["316249678\u2014SFB 1279"]}]},{"name":"International Graduate School in Molecular Medicine Ulm (IGradU)","award":["251293561\u2014SFB 1149"],"award-info":[{"award-number":["251293561\u2014SFB 1149"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Toxins"],"abstract":"<jats:p>The binary Clostridium (C.) botulinum C2 toxin consists of two non-linked proteins. The proteolytically activated binding\/transport subunit C2IIa forms barrel-shaped homoheptamers, which bind to cell surface receptors, mediate endocytosis, and translocate the enzyme subunit C2I into the cytosol of target cells. Here, we investigate whether C2IIa can be harnessed as a transporter for proteins\/enzymes fused to polycationic tags, as earlier demonstrated for the related anthrax toxin transport subunit PA63. To test C2IIa-mediated transport in cultured cells, reporter enzymes are generated by fusing different polycationic tags to the N- or C-terminus of other bacterial toxins\u2019 catalytic A subunits. C2IIa as well as PA63 deliver N-terminally polyhistidine-tagged proteins more efficiently compared to C-terminally tagged ones. However, in contrast to PA63, C2IIa does not efficiently deliver polylysine-tagged proteins into the cytosol of target cells. Moreover, untagged enzymes with a native cationic N-terminus are efficiently transported by both C2IIa and PA63. In conclusion, the C2IIa-transporter serves as a transport system for enzymes that harbor positively charged amino acids at their N-terminus. The charge distribution at the N-terminus of cargo proteins and their ability to unfold in the endosome and subsequently refold in the cytosol determine transport feasibility and efficiency.<\/jats:p>","DOI":"10.3390\/toxins15060390","type":"journal-article","created":{"date-parts":[[2023,6,9]],"date-time":"2023-06-09T02:59:57Z","timestamp":1686279597000},"page":"390","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["The Clostridium botulinum C2 Toxin Subunit C2IIa Delivers Enzymes with Positively Charged N-Termini into the Cytosol of Target Cells"],"prefix":"10.3390","volume":"15","author":[{"given":"Sebastian","family":"Heber","sequence":"first","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joscha","family":"Borho","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8997-866X","authenticated-orcid":false,"given":"Nicole","family":"Stadler","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fanny","family":"Wondany","sequence":"additional","affiliation":[{"name":"Institute of Biophysics, Ulm University, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irina","family":"K\u00f6nig","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2739-4172","authenticated-orcid":false,"given":"Jens","family":"Michaelis","sequence":"additional","affiliation":[{"name":"Institute of Biophysics, Ulm University, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3571-695X","authenticated-orcid":false,"given":"Panagiotis","family":"Papatheodorou","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Holger","family":"Barth","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4356-6579","authenticated-orcid":false,"given":"Maximilian","family":"Fellermann","sequence":"additional","affiliation":[{"name":"Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, 89081 Ulm, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"390","DOI":"10.1038\/322390a0","article-title":"Botulinum C2 Toxin ADP-Ribosylates Actin","volume":"322","author":"Aktories","year":"1986","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1007\/s00210-002-0626-y","article-title":"The Uptake Machinery of Clostridial Actin ADP-Ribosylating Toxins--a Cell Delivery System for Fusion Proteins and Polypeptide Drugs","volume":"366","author":"Barth","year":"2002","journal-title":"Naunyn-Schmiedeberg\u2019s Arch. 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