Difference between revisions of "Part:BBa J64822"

Latest revision as of 08:12, 12 October 2022

P.aeruginosa phz operon activator

phzR / qscR activator of phz operon, which synthesizes phenazine and pyocyanin.

Contribution: New documentation from Evry_Paris-Saclay 2022

Phenazines, which are polyaromatic secondary metabolites, are known as compounds with high redox activity [1]. These secondary metabolites are produced by a variety of bacteria, especially Pseudomonas species. Three endogenous phenazines are known to be produced by Pseudomonas aeruginosa, including pyocyanin, phenazine-1-carboxylic acid, and 1-hydroxyphenazine. The combination and variety of functional groups added also determine the redox potential and solubility of these compounds, thus affecting their biological activity [1].

Phz operon which produces phenazine-1-carboxylic acid is, in the Pseudomonas aeruginosa's genome, preceded by two genes phzR and phzI. Those genes are involved in the its regulation.

The phz operon is controlled at the transcriptional level by a ligand-dependent transcription factor called PhzR or QscR [2]. This activator requires a molecular signal, an acyl-homoserine lactone, synthesised by the action of PhzI, which is an acyl-HSL synthase [3,4].

PhzR/QscR is an approximately symmetrical dimer with a unique configuration of the two domains in each chain. The QscR dimer appears poised to bind DNA. The acyl chain of the AHL is in close proximity to the dimerization interfaces. PhzR/QscR polypeptides have the general structure of the LuxR family consisting of two functional domains, an N-terminal LBD and a C-terminal DBD, the dimer has unique features that have not been seen in any of the LuxR family structures determined to date [5].

References

[1] Chen J-J, Chen W, He H, Li D-B, Li W-W, Xiong L, Yu H-Q. Manipulation of Microbial Extracellular Electron Transfer by Changing Molecular Structure of Phenazine-Type Redox Mediators. Environmental Science & Technology (2013) 47: 1033–1039.

[2] Pang B, Liu T, Zhang W, Ye F, Shang C. Cloning and Characterization of phzR Gene from Pseudomonas aeruginosa. Current Microbiology (2021) 78: 1482–1487.

[3] Khan SR, Mavrodi DV, Jog GJ, Suga H, Thomashow LS, Farrand SK. Activation of the phz operon of Pseudomonas fluorescens 2-79 requires the LuxR homolog PhzR, N-(3-OH-Hexanoyl)-L-homoserine lactone produced by the LuxI homolog PhzI, and a cis-acting phz box. Journal of Bacteriology (2005) 187: 6517–6527.

[4] Selin C, Fernando WGD, de Kievit T. The PhzI/PhzR quorum-sensing system is required for pyrrolnitrin and phenazine production, and exhibits cross-regulation with RpoS in Pseudomonas chlororaphis PA23. Microbiology (Reading, England) (2012) 158: 896–907.

[5] Lintz MJ, Oinuma K, Wysoczynski CL, Greenberg EP, Churchill MEA. Crystal structure of QscR, a Pseudomonas aeruginosa quorum sensing signal receptor. Proceedings of the National Academy of Sciences of the United States of America (2011) 108: 15763–15768.

Sequence and Features