Genetic Characterization of Clostridium botulinum Type A Containing Silent Type B Neurotoxin Gene Sequences (*)
- Roger A. Hutson(1),
- Yongtai Zhou(2),
- Matthew D. Collins(1),
- Eric A. Johnson(2),
- Charles L. Hatheway(3)(§) and
- Hiroshi Sugiyama(2)
- From the (1)Biological and Biotechnical Science Research Council, Institute of Food Research, Reading Laboratory, Earley Gate, Reading RG6 6BZ, United Kingdom, the
- (2)Departments of Food Microbiology and Toxicology and Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, and the
- (3)Centers for Disease Control and Prevention, Atlanta, Georgia 30333
- ↵§ To whom correspondence should be addressed: DBMD, NCID, MS C07, Centers for Disease Control and Prevention, 1600 Clifton Rd., N.E., Atlanta, GA 30333. Tel.: 404-639-3867; Fax: 404-639-3333; clh2{at}ciddbd2.em.cdc.gov
Abstract
A recent study detected genes encoding type B botulinum neurotoxin in some type A strains of Clostridium botulinum that exhibit no type B toxin activity. In this study, we investigated the presence, structure, linkage, and organization of genes encoding botulinum neurotoxin (BoNT) and other components of the progenitor complex. Sequence analysis showed that the silent BoNT/B gene is highly related to that from authentic proteolytic type B C. botulinum. However, a stop signal and deletions were found within the sequence. A non-toxin nonhemagglutinin gene (NTNH) was mapped immediately upstream of both the BoNT/A and silent BoNT/B genes. Significantly the NTNH gene adjacent to the defective BoNT/B gene was “chimeric,” the 5‘- and 3‘-regions of the gene had high homology with corresponding regions of the type B NTNH gene, while the 471-amino acid sequence in the central region was identical to NTNH of type A. Hemagglutinin genes HA-33 and HA-II were not found adjacent to the NTNH/A gene, but instead there was an unidentified open reading frame previously reported in strains of C. botulinum types E and F. By contrast HA-II, HA-33, and NTNH genes were located immediately upstream of the silent BoNT/B gene. Pulsed-field gel electrophoretic analysis of chromosomal DNA digests indicated the distance between type A and B gene clusters to be less than 40 kilobases.
Footnotes
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↵* Research at the University of Wisconsin was sponsored by sponsors of the Food Research Institute and a Hatch grant. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) X87848[GenBank]-X87850[GenBank].
- Received September 20, 1995.
- Revision received February 19, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
