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The genes coding for enterocin EJ97 production by Enterococcus faecalis EJ97 are located on a conjugative plasmid.
Marina Sánchez-Hidalgo1, Mercedes Maqueda, Antonio Gálvez
1Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Fuentenueva s/n, 18071-Granada, Spain.
Applied and Environmental Microbiology
|March 7, 2003
Summary
Enterococcus faecalis EJ97 produces enterocin EJ97, a novel cationic bacteriocin. Its genetic determinants are located on a composite transposon, suggesting a new class of bacteriocins with unique secretion mechanisms.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Enterococcus faecalis EJ97 produces a cationic bacteriocin, enterocin EJ97.
- Bacteriocins are ribosomally synthesized antimicrobial peptides with diverse structures and functions.
- Understanding bacteriocin production mechanisms is crucial for developing novel antimicrobial strategies.
Purpose of the Study:
- To elucidate the genetic basis of enterocin EJ97 production in Enterococcus faecalis EJ97.
- To characterize the novel bacteriocin and its associated genetic elements.
- To investigate the potential for a new class of bacteriocins with unique secretion mechanisms.
Main Methods:
- Automated microsequencing of enterocin EJ97 after enzymatic and chemical digestion.
- Plasmid transfer experiments to identify the genetic determinants of bacteriocin production.
- Cloning, sequencing, and analysis of the DNA region containing the enterocin EJ97 genes.
- Bioinformatic analysis to identify open reading frames (ORFs) and their putative functions.
Main Results:
- The complete amino acid sequence of enterocin EJ97 was determined.
- The genetic determinants of enterocin EJ97 were localized to an 11.3-kb DNA fragment on plasmid pEJ97.
- This region contains the structural gene (ej97A) and several ORFs (ej97B, ej97C, ej97D) with putative functions.
- A transposon-like structure (tnp) with similarities to known mobile genetic elements was identified flanking the enterocin EJ97 module.
- Homologies to ATP-binding cassette transporters were found in Ej97B, suggesting a novel secretion mechanism.
Conclusions:
- Enterocin EJ97 represents a novel class of bacteriocins with a unique secretion mechanism.
- The genetic locus for enterocin EJ97 is part of a composite transposon, indicating potential for horizontal gene transfer.
- The plasmid pEJ97 shares homology with other conjugative plasmids in E. faecalis, suggesting a common evolutionary origin.