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New iron acquisition system in Bacteroidetes.

  • Manfredi P Biozentrum der Universität Basel, Basel, Switzerland.
  • Lauber F Biozentrum der Universität Basel, Basel, Switzerland Université de Namur, Namur, Belgium.
  • Renzi F Biozentrum der Universität Basel, Basel, Switzerland Université de Namur, Namur, Belgium.
  • Hack K Université de Namur, Namur, Belgium.
  • Hess E Université de Namur, Namur, Belgium.
  • Cornelis GR Biozentrum der Universität Basel, Basel, Switzerland Université de Namur, Namur, Belgium guy.cornelis@unamur.be.
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  • 2014-11-05
Published in:
  • Infection and immunity. - 2015
Bacteroidetes
Gram-Negative Bacterial Infections
Humans
Iron
Membrane Transport Proteins
Multigene Family
Serum
English Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group.
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  • English
Open access status
bronze
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https://sonar.ch/global/documents/124325
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