Functional analysis of a bacitracin resistance determinant located on ICECp1, a novel Tn916-like element from a conjugative plasmid in Clostridium perfringens.
Bacitracins are mixtures of structurally related cyclic polypeptides with antibiotic properties. They act by interfering with the biosynthesis of the bacterial cell wall. In this study, we analyzed an avian necrotic enteritis strain of Clostridium perfringens that was resistant to bacitracin and produced NetB toxin. We identified a bacitracin resistance locus that resembled a bacitracin resistance determinant from Enterococcus faecalis. It contained the structural genes bcrABD and a putative regulatory gene, bcrR. Mutagenesis studies provided evidence that both bcrA and bcrB are essential for bacitracin resistance, and that evidence was supported by the results of experiments in which the introduction of both the bcrA and bcrB genes into a bacitracin-susceptible C. perfringens strain was required to confer bacitracin resistance. The wild-type strain was shown to contain at least three large, putatively conjugative plasmids, and the bcrRABD locus was localized to an 89.7-kb plasmid, pJIR4150. This plasmid was experimentally shown to be conjugative and was sequenced. The sequence revealed that it also carries a tpeL toxin gene and is related to the pCW3 family of conjugative antibiotic resistance and toxin plasmids from C. perfringens. The bcr genes were located on a genetic element, ICECp1, which is related to the Tn916 family of integrative conjugative elements (ICEs). ICECp1 appears to be the first Tn916-like element shown to confer bacitracin resistance. In summary, we identified in a toxin-producing C. perfringens strain a novel mobile bacitracin resistance element which was experimentally shown to be essential for bacitracin resistance and is carried by a putative ICE located on a conjugative plasmid.
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia.
Xiaoyan
X
Han
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia College of Animal Husbandry and Veterinary Medicine, Henan Agricultural University, Zhengzhou, People's Republic of China.
Xiang-Dang
XD
Du
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia.
Luke
L
Southey
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia Victorian Bioinformatics Consortium and Victorian Life Sciences Computation Initiative, Monash University, Clayton, Victoria, Australia.
Dieter M
DM
Bulach
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia Victorian Bioinformatics Consortium and Victorian Life Sciences Computation Initiative, Monash University, Clayton, Victoria, Australia.
Torsten
T
Seemann
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia.
Xu-Xia
XX
Yan
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia.
Trudi L
TL
Bannam
Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Clayton, Victoria, Australia julian.rood@monash.edu.
Julian I
http://orcid.org/0000-0003-2126-7209
JI
Rood
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001414:Bacitracin / Q000494:pharmacology*; D003016:Clostridium perfringens / Q000187:drug effects / Q000235:genetics*; D003227:Conjugation, Genetic / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D010957:Plasmids / Q000235:genetics
D000900:Anti-Bacterial Agents; D001414:Bacitracin