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BqsR/BqsS Constitute a Two-Component System That Senses Extracellular Fe(II) in Pseudomonas aeruginosa

Kreamer, Naomi N. K. and Wilks, Jessica C. and Marlow, Jeffrey J. and Coleman, Maureen L. and Newman, Dianne K. (2012) BqsR/BqsS Constitute a Two-Component System That Senses Extracellular Fe(II) in Pseudomonas aeruginosa. Journal of Bacteriology, 194 (5). pp. 1195-1204. ISSN 0021-9193. PMCID PMC3294787. doi:10.1128/JB.05634-11.

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Pseudomonas aeruginosa is a ubiquitous Gram-negative bacterium best known as the predominant opportunistic pathogen infecting the lungs of cystic fibrosis patients. In this context, it is thought to form biofilms, within which locally reducing and acidic conditions can develop that favor the stability of ferrous iron [Fe(II)]. Because iron is a signal that stimulates biofilm formation, we performed a microarray study to determine whether P. aeruginosa strain PA14 exhibits a specific transcriptional response to extracellular Fe(II). Among the genes that were most upregulated in response to Fe(II) were those encoding the two-component system BqsR/BqsS, previously identified for its role in P. aeruginosa strain PAO1 biofilm decay (13); here, we demonstrate its role in extracellular Fe(II) sensing. bqsS and bqsR form an operon together with two small upstream genes, bqsP and bqsQ, and one downstream gene, bqsT. BqsR/BqsS sense extracellular Fe(II) at physiologically relevant concentrations (>10 μM) and elicit a specific transcriptional response, including its autoregulation. The sensor distinguishes between Fe(II), Fe(III), and other dipositive cations [Ca(II), Cu(II), Mg(II), Mn(II), Zn(II)] under aerobic or anaerobic conditions. The gene that is most upregulated by BqsR/BqsS, as measured by quantitative reverse transcription-PCR (qRT-PCR), is PA14_04180, which is predicted to encode a periplasmic oligonucleotide/oligosaccharide-binding domain (OB-fold) protein. Coincident with phenazine production during batch culture growth, Fe(II) becomes the majority of the total iron pool and bqsS is upregulated. The existence of a two-component system that senses Fe(II) indicates that extracellular Fe(II) is an important environmental signal for P. aeruginosa.

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Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2012 American Society for Microbiology. Received 1 July. 2011 Accepted 14 December 2011. Published ahead of print 22 December 2011. We thank the Howard Hughes Medical Institute (HHMI) for supporting this work. D.K.N. is an HHMI investigator. N.K. was supported by an NIH training grant (GM07616). J.C.W. and J.J.M. were supported by NSF graduate fellowships.
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Howard Hughes Medical Institute (HHMI)UNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Issue or Number:5
PubMed Central ID:PMC3294787
Record Number:CaltechAUTHORS:20120323-082322420
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Official Citation:BqsR/BqsS Constitute a Two-Component System That Senses Extracellular Fe(II) in Pseudomonas aeruginosa Naomi N. K. Kreamer, Jessica C. Wilks, Jeffrey J. Marlow, Maureen L. Coleman, and Dianne K. Newman J. Bacteriol. March 2012 194:1195-1204; published ahead of print 22 December 2011 , doi:10.1128/JB.05634-11
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29818
Deposited By: Ruth Sustaita
Deposited On:23 Mar 2012 15:53
Last Modified:09 Nov 2021 19:30

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