Characterization of the genes encoding the botulinum neurotoxin complex in a strain of Clostridium botulinum producing type B and F neurotoxins.
The organization of the clusters of genes encoding proteins of the botulinum neurotoxin (BoNT) progenitor complex was elucidated in a strain of Clostridium botulinum producing type B and F neurotoxins. With PCR and sequencing strategies, the type B BoNT-gene cluster was found to be composed of genes encoding BoNT/B, nontoxic nonhemagglutinin component (NTNH), P-21, and the hemagglutinins HA-33, HA-17, and HA-70, whereas the type F BoNT-gene cluster has genes encoding BoNT/F, NTNH, P-47, and P-21. Comparative sequence analysis showed that BoNT/F in type BF strain 3281 shares highest homology with BoNT/F of non-proteolytic (group II) C. botulinum whereas NTNH and P-21 in the type F cluster of strain 3281 are more similar to the corresponding proteins in proteolytic (group I) type F C. botulinum. These findings indicate diverse evolutionary origins for genes encoding BoNT/F and its associated non-toxic proteins, although the genes are contiguous. By contrast, sequence comparisons indicate that genes encoding BoNT/B and associated non-toxic proteins in strain 3281 possess a similar evolutionary origin. It was demonstrated that the genes present in the BoNT/B gene cluster of this type BF strain show exceptionally high homology with the equivalent genes in the silent BoNT/B gene cluster of C. botulinum type A(B), possibly indicating their common ancestry.
Department of Microbiology, Institute of Food Research, Earley Gate, Whiteknights Road, Reading, RG6 6BZ, UK.
J A
JA
Santos-Buelga
M D
MD
Collins
A K
AK
East
D001483:Base Sequence; D001905:Botulinum Toxins / Q000096:biosynthesis / Q000235:genetics*; D019274:Botulinum Toxins, Type A; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003014:Clostridium botulinum / Q000235:genetics* / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D005798:Genes, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
C096323:rimabotulinumtoxinB; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A; C096321:botulinum toxin type F