Translocation domain of botulinum neurotoxin A subtype 2 potently induces entry into neuronal cells. (14th May 2020)

• Record Type: Journal Article
• Authors: Kohda, Tomoko; Tsukamoto, Kentaro; Torii, Yasushi; Kozaki, Shunji; Mukamoto, Masafumi
• Is Part Of: Microbiology and immunology. Volume 64:Number 7(2020)
• Page Start: 502
• Page End: 511
• Publication Date: 2020-05-14
• Subjects: botulinum neurotoxin -- potency -- SNAP‐25 -- subtypes -- translocation domain; Microbiology -- Periodicals; Immunology -- Periodicals; Allergy and Immunology -- Periodicals; Microbiology -- Periodicals; Microbiologie -- Périodiques; Immunologie -- Périodiques; 579
• DOI: 10.1111/1348-0421.12796
• Languages: English
• ISSNs: 0385-5600

Abstract

Abstract: Botulinum neurotoxin (BoNT) is the causative agent of botulism in humans and animals. Only BoNT serotype A subtype 1 (BoNT/A1) is used clinically because of its high potency and long duration of action. BoNT/A1 and BoNT/A subtype 2 (BoNT/A2) have a high degree of amino acid sequence similarity in the light chain (LC) (96%), whereas their N‐and C‐terminal heavy chain (HN and HC ) differ by 13%. The LC acts as a zinc‐dependent endopeptidase, HN as the translocation domain, and HC as the receptor‐binding domain. BoNT/A2 and BoNT/A1 had similar potency in the mouse bioassay, but BoNT/A2 entered faster and more efficiently into neuronal cells. To identify the domains responsible for these characteristics, HN of BoNT/A1 and BoNT/A2 was exchanged to construct chimeric BoNT/A121 and BoNT/A212. After expression in Escherichia coli, chimeric and wild‐type BoNT/As were purified as single‐chain proteins and activated by conversion to disulfide‐linked dichains. The toxicities of recombinant wild‐type and chimeric BoNT/As were similar, but dropped to 60% compared with the values of native BoNT/As. The relative orders of SNAP‐25 cleavage activity in neuronal cells and toxicity differed. BoNT/A121 and recombinant BoNT/A2 have similar SNAP‐25 cleavage activity. BoNT/A2 HN is possibly responsible for the higher potency of BoNT/A2 than BoNT/A1.