Open AccessMolecular characterization of virulence defects in Bacillus thuringiensis mutants
Author(s) -
Wang Jinhong,
Steggles James R.,
Ellar David J.
Publication year - 2008
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2007.01061.x
Subject(s) - orfs , biology , genetics , transposable element , gene , virulence , mutant , locus (genetics) , transposon mutagenesis , gene cluster , homology (biology) , bacillus thuringiensis , plasmid , sequence analysis , open reading frame , peptide sequence , bacteria
Sequence analysis of a virulence‐attenuated Bacillus thuringiensis signature tagged mutant 6F8 led to the identification of an 18 182 bp locus encoding 29 potential protein‐coding ORFs. Thirteen of the 29 putative ORFs were found to share extensive homology with genes on plasmid pE33L466 of the pathogenic Bacillus cereus E33L strain. Nine ORFs were not only found in a cluster, but also in the same gene order, in both organisms. A number of mobile elements, including a transposon Tn 4430 , a novel IS 231 family insertion sequence IS Bth4 and various phage‐related proteins, were found flanking this conserved gene cluster. These features of the 6F8 locus suggested that it might have undergone several DNA insertions from different sources by horizontal gene transfer. Transcriptional analyses of the 6F8 locus revealed that ORFs 1–23 were cotranscribed as a single transcript. Null mutants were constructed to investigate the function of the sequences flanking the signature‐tagged mutagenesis insertion sites. Competition assays performed with the wild‐type and null mutants demonstrated that the Tn 4430 transposon element plays an important role in the full virulence of B. thuringiensis during Manduca sexta infection. This study provides the first experimental evidence that a Tn 4430 family transposon is directly associated with B. thuringiensis virulence.