Hydroxamate Siderophores of
            <i>Histoplasma capsulatum</i>

Howard, Dexter H.; Rafiee, Ramin; Tiwari, Anupama; Faull, Kym F.

doi:10.1128/iai.68.4.2338-2343.2000

Cited by 62 publications

(45 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In contrast, after growth under iron-replete conditions, siderophore activity was not detected with ferric perchlorate and M. flavescens JG-9 growth was not stimulated (data not shown). These regulatory patterns are consistent with previous results of individual expression of siderophores or reducing agents (20,46).…”

Section: Resultssupporting

confidence: 81%

Potential Role for Extracellular Glutathione-Dependent Ferric Reductase in Utilization of Environmental and Host Ferric Compounds byHistoplasma capsulatum

Timmerman

Woods

2001

Infect Immun

View full text Add to dashboard Cite

The mammalian host specifically limits iron during Histoplasma capsulatum infection, and fungal acquisition of iron is essential for productive infection. H. capsulatum expresses several iron acquisition mechanisms under iron-limited conditions in vitro. These components include hydroxamate siderophores, extracellular glutathione-dependent ferric reductase enzyme, extracellular nonproteinaceous ferric reductant(s), and cell surface ferric reducing agent(s). We examined the relationship between these mechanisms and a potential role for the extracellular ferric reductase in utilization of environmental and host ferric compounds through the production of free, soluble Fe(II). Siderophores and ferric reducing agents were coproduced under conditions of iron limitation. The H. capsulatum siderophore dimerum acid and the structurally similar basidiomycete siderophore rhodotorulic acid acted as substrates for the ferric reductase, and rhodotorulic acid removed Fe(III) bound by transferrin. The mammalian Fe(III)-binding compounds hemin and transferrin served both as substrates for the ferric reductase and as iron sources for yeast-phase growth at neutral pH. In the case of transferrin, there was a correlation between the level of iron saturation and efficacy for both of these functions. Our data are not consistent with an entirely pH-dependent mechanism of iron acquisition from transferrin, as has been suggested to occur in the macrophage phagolysosome. The foreign siderophore ferrioxamine B also acted as a substrate for the ferric reductase, while the foreign siderophore ferrichrome did not. Both ferrioxamine and ferrichrome served as iron sources for yeast-and mold-phase growth, the latter presumably by some other acquisition mechanism(s).

show abstract

Section: Resultssupporting

confidence: 81%

Potential Role for Extracellular Glutathione-Dependent Ferric Reductase in Utilization of Environmental and Host Ferric Compounds byHistoplasma capsulatum

Timmerman

Woods

2001

Infect Immun

View full text Add to dashboard Cite

show abstract

“…In order to exclude artificial methylation during the isolation procedure, extraction and purification were also carried out using ethanol and acetone, respectively, and the same results were obtained. A methylated coprogen B has been previously isolated from Histoplasma capsulatum (Howard et al, 2000) but no structural elucidation has been performed. Coprogen and coprogen B were identified by comparison of fragmentation spectra obtained by MS-MS and comparison of 1D NMR data with reference substances.…”

Section: Magnaporthe Grisea Produces Siderophores Of the Hydroxamate mentioning

confidence: 99%

Siderophores Produced by Magnaporthe grisea in the Presence and Absence of Iron

Antelo

Hof

Welzel

et al. 2006

Zeitschrift Für Naturforschung C

View full text Add to dashboard Cite

An analysis of siderophores produced by Magnaporthe grisea revealed the presence of one intracellular storage siderophore, ferricrocin, and four coprogen derivatives secreted into the medium under iron depletion. Structural analysis showed that the compounds are coprogen, coprogen B, 2-N-methylcoprogen and 2-Nmethylcoprogen B. Siderophore production under low and high iron conditions was quantified.

show abstract

“…Iron limitation in H. capsulatum induces the production and secretion of hydroxamate siderophores, which act as lowmolecular-weight ferric iron chelators (3,16). Additionally, low iron levels have been shown to induce a reductive iron assimilation pathway (36,37).…”

mentioning

confidence: 99%

SRE1 Regulates Iron-Dependent and -Independent Pathways in the Fungal Pathogen Histoplasma capsulatum

et al. 2012

View full text Add to dashboard Cite

Regulation of iron acquisition genes is critical for microbial survival under both iron-limiting conditions (to acquire essential iron) and iron-replete conditions (to limit iron toxicity). In fungi, iron acquisition genes are repressed under iron-replete conditions by a conserved GATA transcriptional regulator. Here we investigate the role of this transcription factor, Sre1, in the cellular responses of the fungal pathogen Histoplasma capsulatum to iron. We showed that cells in which SRE1 levels were diminished by RNA interference were unable to repress siderophore biosynthesis and utilization genes in the presence of abundant iron and thus produced siderophores even under iron-replete conditions. Mutation of a GATA-containing consensus site found in the promoters of these genes also resulted in inappropriate gene expression under iron-replete conditions. Microarray analysis comparing control and SRE1-depleted strains under conditions of iron limitation or abundance revealed both ironresponsive genes and Sre1-dependent genes, which comprised distinct but overlapping sets. Iron-responsive genes included those encoding putative oxidoreductases, metabolic and mitochondrial enzymes, superoxide dismutase, and nitrosative-stressresponse genes; Sre1-dependent genes were of diverse functions. Genes regulated by iron levels and Sre1 included all of the siderophore biosynthesis genes, a gene involved in reductive iron acquisition, an iron-responsive transcription factor, and two catalases. Based on transcriptional profiling and phenotypic analyses, we conclude that Sre1 plays a critical role in the regulation of both traditional iron-responsive genes and iron-independent pathways such as regulation of cell morphology. These data highlight the evolving realization that the effect of Sre1 orthologs on fungal biology extends beyond the iron regulon.

show abstract

Hydroxamate Siderophores of Histoplasma capsulatum

Cited by 62 publications

References 23 publications

Potential Role for Extracellular Glutathione-Dependent Ferric Reductase in Utilization of Environmental and Host Ferric Compounds byHistoplasma capsulatum

Potential Role for Extracellular Glutathione-Dependent Ferric Reductase in Utilization of Environmental and Host Ferric Compounds byHistoplasma capsulatum

Siderophores Produced by Magnaporthe grisea in the Presence and Absence of Iron

SRE1 Regulates Iron-Dependent and -Independent Pathways in the Fungal Pathogen Histoplasma capsulatum

Contact Info

Product

Resources

About