Complete nucleotide sequence of insertion element IS4351 from Bacteroides fragilis

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• The Bacteroides fragilis R plasmid pBF4 harbors the ermF gene, conferring resistance to macrolide, lincosamide, and streptogramin B antibiotics.
• Directly repeated sequences flanking mobile genetic elements are crucial for their function and identification.

Purpose of the Study:

• To characterize a novel insertion sequence (IS) element associated with the ermF gene in Bacteroides fragilis.
• To determine the origin and transposition capabilities of this putative IS element.

Main Methods:

• Nucleotide sequencing and genetic analysis of the flanking regions of the ermF gene.
• Southern blot hybridization to detect homologous sequences in bacterial DNA.
• Complementation assays in E. coli to demonstrate transposition activity.
• Restriction endonuclease mapping for characterization of recombinant plasmids.

Main Results:

• A 1,155-base-pair IS element, designated IS4351, was identified.
• IS4351 possesses terminal-inverted repeats and overlapping open reading frames, characteristic of IS elements.
• Homologous sequences were found in B. fragilis chromosomal DNA, suggesting a bacterial origin.
• Transposition of IS4351 was successfully demonstrated in a recA E. coli host.

Conclusions:

• IS4351 is a novel insertion sequence element originating from Bacteroides.
• This IS element has the capacity for transposition, contributing to genome plasticity and potentially the spread of antibiotic resistance genes.