SawR a new regulator controlling pyomelanin synthesis in Pseudomonas aeruginosa

Yossi Ben-David, Elena Zlotnik, Itzhak Zander, Gal Yerushalmi, Sivan Shoshani, Ehud Banin

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Surface Acoustic Waves (SAW) were previously shown to inhibit biofilm formation, increase bacterial susceptibility to antibiotic treatment and alter the transcription pattern of Pseudomonas aeruginosa. Here we characterize one gene, sawR (PA3133), that is highly overexpressed when P. aeruginosa is exposed to SAW. SawR is a putative transcription factor belonging to the TetR regulator family. When overexpressed sawR causes numerous phenotypes, including the accumulation of a brown pigment which we identified as pyomelanin. In this study we describe how sawR regulates pyomelanin synthesis. We show that sawR down-regulates the expression levels of hmgA and this causes the accumulation of homogentisic acid which in turn undergoes oxidation and polymerization to pyomelanin. Using bioinformatics, we were able to identify a specific amino acid, arginine 23, which is found within the sawR DNA binding domain and is crucial for its regulatory activity. Our results indicate that sawR does not affect any other genes in the phenylalanine/tyrosine metabolic pathway and its repressive ability on hmgA is not mediated by the hmgA repressor PA2010 (i.e. hmgR). Taken together, our results shed light on the regulatory cascade controlling pyomelanin synthesis and uncover yet another unknown regulator involved in its regulation.

Original languageEnglish
Pages (from-to)91-98
Number of pages8
JournalMicrobiological Research
StatePublished - Jan 2018

Bibliographical note

Funding Information:
The work was partially funded by the Dyna and Fala Weinstock Foundation . This work is part of the fulfillment required for Y.B.D. Ph.D. thesis.

Publisher Copyright:
© 2017 Elsevier GmbH


  • Bacteria
  • Pigment
  • Pseudomonas aeruginosa
  • Pyomelanin


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