Amphiphilic siderophore production by oil-associating microbes

Kem, Michelle P.; Zane, Hannah K.; Springer, Stephen D.; Gauglitz, Julia M.; Butler, Alison

doi:10.1039/c4mt00047a

Cited by 32 publications

(27 citation statements)

References 47 publications

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“…Although genes encoding siderophore uptake proteins are common in HNLC metagenomes, genes encoding siderophore biosynthesis have yet to be reported . A pair of nonribosomal peptide synthetases (NRPS), ABO_2093 and ABO_2092, were recently implicated in the production of amphibactins by the Gammaproteobacteria Alcanivorax borkumensis [Kem et al, 2014]. We identified similar NRPS genes in the genomes of numerous marine Vibrio, and confirmed amphibactin production by five additional NRPS sequence pairs through laboratory culture experiments (supplementary information).…”

Section: Main Textsupporting

confidence: 50%

Molecular determination of marine iron ligands by mass spectrometry

Boiteau¹

2016

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Abstract:Marine microbes produce a wide variety of metal binding organic ligands that regulate the solubility and availability of biologically important metals such as iron, copper, cobalt, and zinc.In marine environments where the availability of iron limits microbial growth and carbon fixation rates, the ability to access organically bound iron confers a competitive advantage. Thus, the compounds that microbes produced to acquire iron play an important role in biogeochemical carbon and metal cycling. However, the source, abundance, and identity of these compounds are poorly understood. To investigate these processes, sensitive methodologies were developed to gain a compound-specific window into marine iron speciation by combining trace metal clean sample collection and chromatography with inductively coupled plasma mass spectrometry (LC-ICPMS) and electrospray ionization mass spectrometry (LC-ESIMS). Coupled with isotope pattern assisted search algorithms, these tools provide a means to quantify and isolate specific iron binding ligands from seawater and marine cultures, identify them based on their mass and fragmentation spectra, and investigate their metal binding kinetics.Using these techniques, we investigated the distribution and diversity of marine iron binding ligands. In cultures, LC-ICPMS-ESIMS was used to identify new members of siderophore classes produced by marine cyanobacteria and heterotrophic bacteria, including synechobactins and marinobactins. Applications to natural seawater samples from the Pacific Ocean revealed a wide diversity of both known and novel metal compounds that are linked to specific nutrient regimes. Ferrioxamines B, E, and G were identified in productive coastal waters near California and Peru, in oligotrophic waters of the North and South Pacific Gyre, and in association with zooplankton grazers. Siderophore concentrations were up to five-fold higher in iron-deficient offshore waters (9pM) and were dominated by amphibactins, amphiphilic siderophores that partition into cell membranes. Furthermore, synechobactins were detected within nepheloid layers along the continental shelf. These siderophores reflect adaptations that impact dissolved iron bioavailability and thus have important consequences for marine ecosystem community structures and primary productivity. The ability to map and characterize these compounds has opened new opportunities to better understand mechanisms that link metals with the microbes that use them. 4Acknowledgements:

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Section: Main Textsupporting

confidence: 50%

Molecular determination of marine iron ligands by mass spectrometry

Boiteau¹

2016

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“…Advanced organic mass spectrometry (ESI-MS) techniques (McCormack et al, 2003) have shown that desferrioxamines, a family of trihydroxamate siderophores, occur at low-pM concentrations in surface waters throughout much of the Atlantic Ocean (Mawji et al, 2008). However, most marine siderophores are structurally very different from terrestrial analogs, even if they contain the same functional groups (Vraspir and Butler, 2009), driving a search for novel amphiphilic ligands, several of which have now been isolated from Fe-limited cultures (Martinez et al, 2000;Kem et al, 2014), or biosynthesized through genomics . More sophisticated procedures are being developed for detecting organic ligands in seawater, either linking conventional ESI-MS with metal-specific extractions, such as immobilized metal affinity chromatography (Ross et al, 2003) and HPLC-ICP-MS (Boiteau et al, 2013), or relying on the power of ultrahigh-resolution FT-ICR-MS (Waska et al, 2015) for a less targeted approach.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Side-Reaction Coefficient of Desferrioxamine B in Trace-Metal-Free Seawater

Schijf

Burns

2016

Front. Mar. Sci.

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Electrochemical techniques like adsorptive cathodic stripping voltammetry with competitive ligand equilibration (ACSV-CLE) can determine total concentrations of marine organic ligands and their conditional binding constants for specific metals, but cannot identify them. Individual organic ligands, isolated from microbial cultures or biosynthesized through genomics, can be structurally characterized via NMR and tandem MS analysis, but this is tedious and time-consuming. A complementary approach is to compare known properties of natural ligands, particularly their conditional binding constants, with those of model organic ligands, measured under suitable conditions. Such comparisons cannot be meaningfully interpreted unless the side-reaction coefficient (SRC) of the model ligand in seawater is thoroughly evaluated. We conducted series of potentiometric titrations, in non-coordinating medium at seawater ionic strength (0.7 M NaClO 4 ) over a range of metal:ligand molar ratios, to study complexation of the siderophore desferrioxamine B (DFOB) with Mg and Ca, for which it has the highest affinity among the major seasalt cations. From similar titrations of acetohydroxamic acid in the absence and presence of methanesulfonate (mesylate), it was determined that Mg and Ca binding to this common DFOB counter-ion is not strong enough to interfere with the DFOB titrations. Stability constants were measured for all DFOB complexes with Mg and Ca including, for the first time, the bidentate complexes. No evidence was found for Mg and Ca coordination with the DFOB terminal amine. From the improved DFOB speciation, we calculated five SRCs for each of the five (de)protonated forms of DFOB in trace-metal-free seawater, yet we also present a more convenient definition of a single SRC that allows adjustment of all DFOB stability constants to seawater conditions, no matter which of these forms is selected as the "component" (reference species). An example of Cd speciation in seawater containing DFOB illustrates the non-trivial use of different SRCs for polyprotic, polydentate organic ligands.

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“…They are iron (III) chelators that bacteria secrete to scavenge, solubilise and transport iron (III) inside the cell (Borer, Sulzberger, Reichard, & Kraemer, 2005;Neilands, 1984;Rastogi & Sinha, 2009). Amphibactins produced by Alcanivorax borkumensis SK2 are another example of siderophores used by the bacterium to increase biodegradation (Kem, Zane, Springer, Gauglitz, & Butler, 2014).…”

Section: Marine Bacterial Secondary Metabolites: Structure and Functionmentioning

confidence: 99%