Integrase-controlled excision of metal-resistance genomic islands in Acinetobacter baumannii

Zaaima Al Jabri, Roxana Zamudio, Eva Horvath-Papp, Joseph D. Ralph, Zakariya Al-Muharrami, Kumar Rajakumar, Marco R. Oggioni

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Genomic islands (GIs) are discrete gene clusters encoding for a variety of functions including antibiotic and heavymetal resistance, some of which are tightly associated to lineages of the core genome phylogenetic tree. We have investigated the functions of two distinct integrase genes in the mobilization of two metal resistant GIs, G08 and G62, of Acinetobacter baumannii. Real-time PCR demonstrated integrase-dependent GI excision, utilizing isopropyl β-D-1-thiogalactopyranoside IPTG-inducible integrase genes in plasmid-based mini-GIs in Escherichia coli. In A. baumannii, integrase-dependent excision of the original chromosomal GIs could be observed after mitomycin C induction. In both E. coli plasmids and A. baumannii chromosome, the rate of excision and circularization was found to be dependent on the expression level of the integrases. Susceptibility testing in A. baumannii strain ATCC 17978, A424, and their respective ΔG62 and ΔG08 mutants confirmed the contribution of the GI-encoded efflux transporters to heavy metal decreased susceptibility. In summary, the data evidenced the functionality of two integrases in the excision and circularization of the two Acinetobacter heavy-metal resistance GIs, G08 and G62, in E. coli, as well as when chromosomally located in their natural host. These recombination events occur at different frequencies resulting in genome plasticity and may participate in the spread of resistance determinants in A. baumannii.

Original languageEnglish
Article number366
JournalGenes
Volume9
Issue number7
DOIs
Publication statusPublished - Jul 20 2018

Keywords

  • Acinetobacter baumannii
  • Copper resistance
  • Genomic island
  • Integrase
  • Mobile genetic element

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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  • Cite this

    Al Jabri, Z., Zamudio, R., Horvath-Papp, E., Ralph, J. D., Al-Muharrami, Z., Rajakumar, K., & Oggioni, M. R. (2018). Integrase-controlled excision of metal-resistance genomic islands in Acinetobacter baumannii. Genes, 9(7), [366]. https://doi.org/10.3390/genes9070366