The genome sequence of Clostridium botulinum type C neurotoxin-converting phage and the molecular mechanisms of unstable lysogeny

Yoshihiko Sakaguchi, Tetsuya Hayashi*, Ken Kurokawa, Keisuke Nakayama, Kenshiro Oshima, Yukako Fujinaga, Makoto Ohnishi, Eiichi Ohtsubo, Masahira Hattori, Keiji Oguma

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

101 Citations (Scopus)

Abstract

Botulinum neurotoxins (BoNTXs) produced by Clostridium botulinum are among the most poisonous substances known. Of the seven types of BoNTXs, genes for type C1 and D toxins (BoNTX/C1 and D) are carried by bacteriophages. The gene for exoenzyme C3 also resides on these phages. Here, we present the complete genome sequence of c-st, a representative of BoNTX/C1-converting phages. The genome is a linear double-stranded DNA of 185,682 bp with 404-bp terminal direct repeats, the largest known temperate phage genome. We identified 198 potential protein-coding regions, including the genes for production of BoNTX/C1 and exoenzyme C3. Very exceptionally, as a viable bacteriophage, a number of insertion sequences were found on the c-st genome. By analyzing the molecular structure of the c-st genome in lysogens, we also found that it exists as a circular plasmid prophage. These features account for the unstable lysogeny of BoNTX phages, which has historically been called "pseudolysogeny." The PCR scanning analysis of other BoNTX/C1 and D phages based on the c-st sequence further revealed that BoNTX phages comprise a divergent phage family, probably generated by exchanging genomic segments among BoNTX phages and their relatives.

Original languageEnglish
Pages (from-to)17472-17477
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number48
DOIs
Publication statusPublished - 2005 Nov 29
Externally publishedYes

Keywords

  • Bacteriophage
  • Botulinum neurotoxin
  • Insertion sequence
  • Plasmid prophage

ASJC Scopus subject areas

  • Genetics
  • General

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