Siderophore-mediated signaling regulates virulence factor production in Pseudomonasaeruginosa.
Numerous bacteria secrete low molecular weight compounds termed siderophores that have a high affinity for iron ions. Siderophores have a well-documented role as iron-scavenging chemicals, chelating iron ions in the environment whereupon the ferrisiderophores reenter the bacterial cells by means of specific cell-surface receptors. The iron is then released for incorporation into bacterial proteins. Here we show that in addition to its role as an iron-scavenger, the siderophore pyoverdine that is secreted by Pseudomonas aeruginosa regulates the production of at least three virulence factors (exotoxin A, an endoprotease, and pyoverdine itself), which are major contributors to the ability of this bacterium to cause disease. Regulation occurs through a transmembrane signaling system that includes an outer membrane receptor for ferripyoverdine, a signal-transducing protein that is predicted to extend from the periplasm into the cytoplasm, and a sigma factor. Expression of genes that form part of the regulon is triggered by pyoverdine so that this siderophore acts as a signaling molecule to control the production of secreted products. Recognition that a siderophore acts as a signaling molecule has important implications for the understanding of interactions between bacterial cells.
Lamont
Iain L
IL
Department of Biochemistry and Centre for Gene Research, University of Otago, P.O. Box 56, Dunedin, New Zealand. iain.lamont@stonebow.otago.ac.nz
Beare
Paul A
PA
Ochsner
Urs
U
Vasil
Adriana I
AI
Vasil
Michael L
ML
D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D005098:Exotoxins / Q000235:genetics / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000378:metabolism*; D008969:Molecular Sequence Data; D009842:Oligopeptides; D010860:Pigments, Biological / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism*; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D005098:Exotoxins; D007502:Iron Chelating Agents; D009842:Oligopeptides; D010860:Pigments, Biological; D012697:Serine Endopeptidases; D017262:Siderophores; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C042453:pyoverdin; C434495:PrpL endoprotease