High stability ferric chelates result in decreased iron uptake by the green alga<i>Chlorella kessleri</i>owing to decreased ferric reductase activity and chelation of ferrous iron

Weger, Harold G.; Lam, Jackie LamJ.; Wirtz, Nikki L.; Walker, Crystal N. WalkerC.N.; Treble, Ron G.

doi:10.1139/b09-063

Cited by 10 publications

(12 citation statements)

References 40 publications

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“…1) in a manner consistent with the decreases associated with increasing HEDTA or HBED concentrations described by Weger et al (2009). Increasing DFB levels also decreased the iron-limited culture growth rates, with 2500 lM supporting poor culture growth (Fig.…”

Section: Resultssupporting

confidence: 78%

“…The above experiments were carried out in the presence and absence of BPDS (when present, final concentration was 500 lM). 500 lM BPDS completely inhibits the growth of Chlorella in the presence of Fe(III)-HEDTA by binding the reduced ferrous iron, preventing uptake by the cells (Weger et al 2009). Bioassays were run over a 116 h time course.…”

Section: Bioassays/growth Experimentsmentioning

confidence: 99%

“…A similar adjustment was necessary when using Fe(III)-HBED as the iron source (molar absorptivity at 535 nm 2560 M -1 cm -1 ; Weger et al 2009). This adjustment was not necessary when using Fe(III)-HEDTA, as the absorption at 535 nm was very low (11.5 M -1 cm -1 ; Weger et al 2009).…”

Section: Ferric Reductase Activitymentioning

confidence: 99%

“…With respect to the reductive iron acquisition mechanism, Weger et al (2009) recently presented a model for the interactions between ferric chelators and ferric reductase activity by iron-limited cells of the green alga Chlorella kessleri. This model suggests that ferric chelators interact with ferric reductase in several ways: (1) Fe(III)-chelates in which the chelator has a higher affinity for Fe(III) will support lower ferric reduction rates, (2) higher affinity chelators will more effectively compete with the Fe(II) transport system for Fe(II) produced by ferric reductase activity, thus decreasing the Fe(II) transport rate, and (3) iron-free higher affinity chelators will directly inhibit ferric reductase activity.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we further examine the model of reductive iron acquisition put forward by Weger et al (2009). Specifically, we examine the potential of potentially common soil and aquatic molecules (siderophores/humic acid analogues, and the herbicide PMG) to both support and inhibit iron acquisition by an organism that uses a reductive (Strategy I) iron acquisition mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators

Sonier

Weger

2010

Biometals

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Iron-limited cells of the green alga Chlorella kesslerii use a reductive mechanism to acquire Fe(III) from the extracellular environment, in which a plasma membrane ferric reductase reduces Fe(III)-chelates to Fe(II), which is subsequently taken up by the cell. Previous work has demonstrated that synthetic chelators both support ferric reductase activity (when supplied as Fe(III)-chelates) and inhibit ferric reductase. In the present set of experiments we extend these observations to naturally-occurring chelators and their analogues (desferrioxamine B mesylate, schizokinen, two forms of dihydroxybenzoic acid) and also two formulations of the commonly-used herbicide N-(phoshonomethyl)glycine (glyphosate). The ferric forms of the larger siderophores (desferrioxamine B mesylate, schizokinen) and Fe(III)-N-(phoshonomethyl)glycine (as the isopropylamine salt) all supported rapid rates of ferric reductase activity, while the iron-free forms inhibited reductase activity. The smaller siderophores/siderophore precursors, 2,3- and 3,4-dihydroxybenzoic acids, did not support high rates of reductase in the ferric form but did inhibit reductase activity in the iron-free form. Bioassays indicated that Fe(III)-chelates that supported high rates of ferric reductase activity also supported a large stimulation in the growth of iron-limited cells, and that an excess of iron-free chelator decreased the growth rate. With respect to N-(phosphonomethyl)glycine, there were differences between the pure compound (free acid form) and the most common commercial formulation (which also contains isopropylamine) in terms of supporting and inhibiting ferric reductase activity and growth. Overall, these results suggest that photosynthetic organisms that use a reductive strategy for iron acquisition both require, and are potentially simultaneously inhibited by, ferric chelators. Furthermore, these results also may provide an explanation for the frequently contradictory results of N-(phosphonomethyl)glycine application to crops: we suggest that low concentrations of this molecule likely solubilize Fe(III), making it available for plant growth, but that higher (but sub-lethal) concentrations decrease iron acquisition by inhibiting ferric reductase activity.

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Section: Resultssupporting

confidence: 78%

Section: Bioassays/growth Experimentsmentioning

confidence: 99%

Section: Ferric Reductase Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators

Sonier

Weger

2010

Biometals

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Iron uptake and storage in the HAB dinoflagellate Lingulodinium polyedrum

et al. 2017

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The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies being distinguished: Strategy I involves the induction of an Fe(III)-chelate reductase (ferrireductase) along with Fe(II) or Fe(III) transporter proteins while strategy II plants have evolved sophisticated systems based on high-affinity, iron specific, binding compounds called phytosiderophores. In contrast, there is little knowledge about the corresponding systems in marine, plant-like lineages. Herein we report a study of the iron uptake and storage mechanisms in the harmful algal bloom dinoflagellate Lingulodinium polyedrum. L. polyedrum is an armored dinoflagellate with a mixotrophic lifestyle and one of the most common bloom species on Southern California coast widely noted for its bioluminescent properties and as a producer of yessotoxins. Short term radio-iron uptake studies indicate that iron is taken up by L. polyedrum in a time dependent manner consistent with an active transport process. Based on inhibitor and other studies it appears that a reductive-oxidative pathway such as that found in yeast and the green alga Chlamydomonas reinhardtii is likely. Of the various iron sources tested vibrioferrin, a photoactive and relatively weak siderophore produced by potentially mutualistic Marinobacter bacterial species, was the most efficient. Other more stable and non-photoactive siderophores such as ferrioxamine E were ineffective. Several pieces of data including long term exposure to Fe using Mössbauer spectroscopy suggest that L. polyedrum does not possess an iron storage system but rather presumably relies on an efficient iron uptake system, perhaps mediated by mutualistic interactions with bacteria.

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Single precursor-based luminescent nitrogen-doped carbon dots and their application for iron (III) sensing

Shah

Jia

et al. 2019

Arabian Journal of Chemistry

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High stability ferric chelates result in decreased iron uptake by the green algaChlorella kessleriowing to decreased ferric reductase activity and chelation of ferrous iron

Cited by 10 publications

References 40 publications

Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators

Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators

Iron uptake and storage in the HAB dinoflagellate Lingulodinium polyedrum

Single precursor-based luminescent nitrogen-doped carbon dots and their application for iron (III) sensing

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