A complex hierarchical quorum-sensing circuitry modulates phenazine gene expression in Pseudomonas aeruginosa

  • Norhan Khairy Abd El-Aziz Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
  • Marwa Ibrahim Abd El-Hamid Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
  • El-sayed Youssef El-Naenaeey Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

Abstract

Introduction: Pseudomonas aeruginosa (P. aeruginosa) modulates the expression of a myriad of virulence factors via two complicated hierarchical quorum-sensing (QS) cascade. This study shed light on the interrelation between P. aeruginosa QS systems and pyocyanin production.


Methodology: Transcription analysis of lasR, rhlR, rhlI and phz genes using quantitative real time-reverse transcriptase PCR (qRT–PCR) assay, followed by sequencing of the autoinducer synthase (lasI gene) were applied for 15 P. aeruginosa strains recovered from diverse animal clinical sources.


Results: Expression studies revealed that most P. aeruginosa strains demonstrated statistically significant differences (p < 0.05) with a very wide range of transcript levels of QS and phz genes in comparison to P. aeruginosa ATCC 27853. We have identified significant positive correlations (r ≥ 0.3) between the expressions of QS and phz genes in eleven analyzed strains, whereas pyocyanin production positively correlated with the expression of lasR only in three strains (r ≥ 0.6). We further found that there was a negative correlation between the transcript levels of QS and phz genes in one bacterial strain. Analysis of lasI sequences showed point mutations explaining the alterations in pyocyanin expression. The deficiencies of lasI, lasR and rhlI with rhlR-dependent expression of phz in one strain were also recorded.


Conclusions: These results provided new insights to the pivotal role of QS signal molecules on pyocyanin production presenting the las system as the dominant regulator.

Author Biographies

Norhan Khairy Abd El-Aziz, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

Lecturer of Bacteriology, Mycology and Immunology
Department of Microbiology
Faculty of veterinary medicine

Marwa Ibrahim Abd El-Hamid, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

Lecturer of Bacteriology, Mycology and Immunology
Department of Microbiology
Faculty of veterinary medicine

El-sayed Youssef El-Naenaeey, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

Professor of Microbiology
Department of Microbiology
Faculty of veterinary medicine

Published
2018-01-10
How to Cite
Abd El-Aziz N, Abd El-Hamid M, El-Naenaeey E (2018) A complex hierarchical quorum-sensing circuitry modulates phenazine gene expression in Pseudomonas aeruginosa. The Journal Of Infection In Developing Countries 11 (12): 919-925. https://doi.org/10.3855/jidc.8775
Section
Original Articles

Keywords

Quorum sensing; pyocyanine; P. aeruginosa; reverse transcriptase PCR