botR/A is a positive regulator of botulinum neurotoxin and associated non-toxin protein genes in Clostridium botulinum A.
The genes of the botulinum neurotoxin A (BoNT) complex are clustered in a locus consisting of two divergent polycistronic operons, one containing the non-toxic, non-haemagglutinin (NTNH) component and bontA genes, the other containing the haemagglutinin (HA) component genes. The two operons are separated by a gene (botR/A, previously called orf21) encoding a 21 kDa protein. A recombinant Clostridium botulinum A strain that overexpresses botR/A was constructed by electroporating strain 62 with the vector pAT19 containing botR/A under the control of its own promoter. The transformed strain produced more BoNT/A and associated non-toxic proteins (ANTPs) and the corresponding mRNAs than the non-transformed strain. Partial inhibition of botR/A by antisense mRNA resulted in lower levels of BoNT/A, NTNH and HA70 and the levels of the corresponding mRNAs. Gel mobility shift assays and immunoprecipitations showed that BotR/A bound to the DNA promoter region upstream from the two BoNT/A complex operons. These results show that botR/A activated transcription of the genes encoding BoNT/A and ANTPs in C. botulinum A by interacting directly with the region promoter, and that the homologous genes in C. botulinum B, C and D presumably have the same function.
Unité des Toxines Microbiennes, Institut Pasteur, Paris, France.
J C
JC
Marvaud
M
M
Gibert
K
K
Inoue
Y
Y
Fujinaga
K
K
Oguma
M R
MR
Popoff
D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001905:Botulinum Toxins / Q000096:biosynthesis / Q000235:genetics* / Q000633:toxicity; D003014:Clostridium botulinum / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D005809:Genes, Regulator; D051379:Mice; D005810:Multigene Family; D009876:Operon; D011401:Promoter Regions, Genetic; D016372:RNA, Antisense / Q000235:genetics; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D017931:DNA Primers; D016372:RNA, Antisense; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001905:Botulinum Toxins