Novel structural elements within the nonproteolytic clostridium botulinum type F toxin gene cluster

Abstract

We sequenced for the first time the complete neurotoxin gene cluster of a nonproteolytic Clostridium botulinum type F. The neurotoxin gene cluster contained a novel gene arrangement that, compared to other C. botulinum neurotoxin gene clusters, lacked the regulatory botR gene and contained an intergenic is element between its orfX2 and orfX3 genes.

FIG. 1.

Botulinum neurotoxin gene cluster arrangements of orfX clusters. Note that the nonproteolytic F6 and E clusters lack the botR regulatory gene, which is present in the proteolytic F1 and A1 to A4 clusters. Although the F6 and A1 clusters both contain an orfX2-orfX3 intergenic spacing that consists of a degenerated is element, the two is sequences are not homologous. The subtype of the bontA gene of strain CDC41370 was designated A1-2 in Fig. 1 of reference (12). The complete neurotoxin gene cluster sequences of bont/F2 to bont/F5 and bont/F7 are not available in GenBank and so could not be included in this report.