Salmochelin, the long-overlooked catecholate siderophore of Salmonella

Müller, Silke I.; Valdebenito, Marianne; Hantke, Klaus

doi:10.1007/s10534-009-9217-4

Cited by 125 publications

(114 citation statements)

References 20 publications

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“…Lipocalin, a protein produced by epithelial cells and in the granules of polymorphonuclear leukocytes, binds to enterobactin and prevents its use as an iron source by enteric bacteria (27). However, salmochelin, which is produced by Salmonella species (55), uropathogenic E. coli (34), and some Klebsiella strains (49), is the glucosylated form of enterobactin and is not bound by the innate immunity protein lipocalin (26). Thus, the ability to modify enterobactin, by the action of the iro locus, leads to escape from the sequestering capabilities of lipocalin.…”

Section: Discussionmentioning

confidence: 99%

ThefbpABCOperon Is Required for Ton-Independent Utilization of Xenosiderophores byNeisseria gonorrhoeaeStrain FA19

2011

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Neisseria gonorrhoeae produces no known siderophores but can employ host-derived, iron-binding proteins, including transferrin and lactoferrin, as iron sources. Given the propensity of this pathogen to hijack rather than synthesize iron-sequestering molecules, we hypothesized that the ability to use siderophores produced by other bacteria, or xenosiderophores, may also play a role in the survival of the gonococcus. Among a panel of diverse siderophores, only the catecholate xenosiderophores enterobactin and salmochelin promoted growth of gonococcal strain FA19. Surprisingly, the internalization pathway was independent of TonB or any of the TonB-dependent transporters. Xenosiderophore-mediated growth was similarly independent of the pilinextruding secretin formed by PilQ and of the hydrophobic-agent efflux system composed of MtrCDE. The fbpABC operon encodes a periplasmic-binding-protein-dependent ABC transport system that enables the gonococcus to transport iron into the cell subsequent to outer membrane translocation. We hypothesized that the FbpABC proteins, required for ferric iron transport from transferrin and lactoferrin, might also contribute to the utilization of xenosiderophores as iron sources. We created mutants that conditionally expressed FbpABC from an IPTG-inducible promoter. We determined that expression of FbpABC was required for growth of gonococcal strain FA19 in the presence of enterobactin and salmochelin. The monomeric component of enterobactin, dihydroxybenzoylserine (DHBS), and the S2 form of salmochelin specifically promoted FbpABC-dependent growth of FA19. This study demonstrated that the gonococcal FbpABC transport system is required for utilization of some xenosiderophores as iron sources and that growth promotion by these ferric siderophores can occur in the absence of TonB or individual TonB-dependent transporters.

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Section: Discussionmentioning

confidence: 99%

ThefbpABCOperon Is Required for Ton-Independent Utilization of Xenosiderophores byNeisseria gonorrhoeaeStrain FA19

2011

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“…In K. pneumoniae, the genes that are required for enterobactin biosynthesis are carried on the chromosome in the entABCDEF gene cluster, while the fepABCDG gene cluster encodes the proteins that mediate its transport, with fepA specifically encoding the uptake receptor (319,320). Importantly, while fepA expression has been shown to be upregulated during K. pneumoniae infection, suggesting an upregulation of enterobactin functionality, enterobactin is neutralized by the host-secreted molecule lipocalin-2 (321, 322).…”

Section: Siderophoresmentioning

confidence: 99%

Klebsiella pneumoniae: Going on the Offense with a Strong Defense

Paczosa

Mecsas

2016

Microbiol Mol Biol Rev

1,295

1,345

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SUMMARYKlebsiella pneumoniaecauses a wide range of infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Historically,K. pneumoniaehas caused serious infection primarily in immunocompromised individuals, but the recent emergence and spread of hypervirulent strains have broadened the number of people susceptible to infections to include those who are healthy and immunosufficient. Furthermore,K. pneumoniaestrains have become increasingly resistant to antibiotics, rendering infection by these strains very challenging to treat. The emergence of hypervirulent and antibiotic-resistant strains has driven a number of recent studies. Work has described the worldwide spread of one drug-resistant strain and a host defense axis, interleukin-17 (IL-17), that is important for controlling infection. Four factors, capsule, lipopolysaccharide, fimbriae, and siderophores, have been well studied and are important for virulence in at least one infection model. Several other factors have been less well characterized but are also important in at least one infection model. However, there is a significant amount of heterogeneity inK. pneumoniaestrains, and not every factor plays the same critical role in all virulentKlebsiellastrains. Recent studies have identified additionalK. pneumoniaevirulence factors and led to more insights about factors important for the growth of this pathogen at a variety of tissue sites. Many of these genes encode proteins that function in metabolism and the regulation of transcription. However, much work is left to be done in characterizing these newly discovered factors, understanding how infections differ between healthy and immunocompromised patients, and identifying attractive bacterial or host targets for treating these infections.

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“…Besides the iroBCDE and iroN plasmid-encoded genes, the entire chromosomally encoded enterobactin cluster is required for salmochelin biosynthesis and transport (113). In addition, the chromosomally encoded TonB complex is needed to transport salmochelin across the outer membrane.…”

Section: Salmochelin Iron Uptake Systemmentioning

confidence: 99%

Plasmid-Encoded Iron Uptake Systems

Lorenzo

Stork

2014

Microbiol Spectr

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Plasmids confer genetic information that benefits the bacterial cells containing them. In pathogenic bacteria, plasmids often harbor virulence determinants that enhance the pathogenicity of the bacterium. The ability to acquire iron in environments where it is limited, for instance the eukaryotic host, is a critical factor for bacterial growth. To acquire iron, bacteria have evolved specific iron uptake mechanisms. These systems are often chromosomally encoded, while those that are plasmid-encoded are rare. Two main plasmid types, ColV and pJM1, have been shown to harbor determinants that increase virulence by providing the cell with essential iron for growth. It is clear that these two plasmid groups evolved independently from each other since they do not share similarities either in the plasmid backbones or in the iron uptake systems they harbor. The siderophores aerobactin and salmochelin that are found on ColV plasmids fall in the hydroxamate and catechol group, respectively, whereas both functional groups are present in the anguibactin siderophore, the only iron uptake system found on pJM1-type plasmids. Besides siderophore-mediated iron uptake, ColV plasmids carry additional genes involved in iron metabolism. These systems include ABC transporters, hemolysins, and a hemoglobin protease. ColV-and pJM1-like plasmids have been shown to confer virulence to their bacterial host, and this trait can be completely ascribed to their encoded iron uptake systems.

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Salmochelin, the long-overlooked catecholate siderophore of Salmonella

Cited by 125 publications

References 20 publications

ThefbpABCOperon Is Required for Ton-Independent Utilization of Xenosiderophores byNeisseria gonorrhoeaeStrain FA19

ThefbpABCOperon Is Required for Ton-Independent Utilization of Xenosiderophores byNeisseria gonorrhoeaeStrain FA19

Klebsiella pneumoniae: Going on the Offense with a Strong Defense

Plasmid-Encoded Iron Uptake Systems

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