Peptide siderophores

Drechsel, Hartmut; Jung, Günther

doi:10.1002/(sici)1099-1387(199805)4:3<147::aid-psc136>3.0.co;2-c

Cited by 128 publications

(81 citation statements)

References 165 publications

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“…Aromatic compounds, including several classes of siderophores (Drechsel and Jung, 1998), strongly absorb UV wavelengths. The presence of Fe can also enhance the UV absorbance of solutions (Weishaar et al, 2003), though the correlations of A260 with DOC and siderophores show that the relationship between Fe(III) and A260 was not produced entirely by this effect.…”

Section: Discussionmentioning

confidence: 99%

Water-table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

et al. 2012

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Abstract. Drained thaw lake basins (DTLB's) are the dominant land form of the Arctic Coastal Plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in these complex landscapes. Here we report the effects of experimental flooding, along with seasonal and spatial variation in soil chemistry and microbial activity in a DTLB. The flooding treatment generally mirrored the effects of natural landscape variation in water-table height due to microtopography. The flooded portion of the basin had lower dissolved oxygen, lower oxidation-reduction potential (ORP) and higher pH, as did lower elevation areas throughout the entire basin. Similarly, soil pore water concentrations of organic carbon and aromatic compounds were higher in flooded and low elevation areas. Dissolved ferric iron (Fe(III)) concentrations were higher in low elevation areas and responded to the flooding treatment in low areas, only. The high concentrations of soluble Fe(III) in soil pore water were explained by the presence of siderophores, which were much more concentrated in low elevation areas. All the aforementioned variables were correlated, showing that Fe(III) is solubilized in response to anoxic conditions. Dissolved carbon dioxide (CO 2 ) and methane (CH 4 ) concentrations were higher in low elevation areas, but showed only subtle and/or seasonally dependent effects of flooding. In anaerobic laboratory incubations, more CH 4 was produced by soils from low and flooded areas, whereas anaerobic CO 2 production only responded to flooding in high elevation areas. Seasonal changes in the oxidation state of solid phase Fe minerals showed that net Fe reduction occurred, especially in topographically low areas. The effects of Fe reduction were also seen in the topographic patterns of pH, as protons were consumed where this process was prevalent. This suite of results can all be attributed to the effect of water table on oxygen availability: flooded conditions promote anoxia, stimulating dissolution and reduction of Fe(III), and to some extent, methanogenesis. However, two lines of evidence indicated the inhibition of methanogenesis by alternative e-acceptors such as Fe(III) and humic substances: (1) ratios of CO 2 :CH 4 evolved from anaerobic soil incubations and dissolved in soil pore water were high; (2) CH 4 concentrations were negatively correlated with the oxidation state of the soluble Fe pool in both topographically high and low areas. A second set of results could be explained by increased soil temperature in the flooding treatment,...

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Section: Discussionmentioning

confidence: 99%

Water-table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

et al. 2012

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“…These environmentally limiting conditions have placed selective pressure on organisms to develop controlled and specific mechanisms to acquire iron. Siderophores are secondary metabolites used to scavenge ferric ion selectively through the formation of soluble chelation complexes (2,3). This structurally diverse group of small molecules contains metalchelating motifs that commonly include hydroxamates, catechols, ␣-hydroxyacids, and heterocycles to bind iron with high affinity.…”

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confidence: 99%

Structure elucidation and biosynthesis of fuscachelins, peptide siderophores from the moderate thermophile Thermobifida fusca

Dimise

Widboom

Bruner

2008

Proc. Natl. Acad. Sci. U.S.A.

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Bacteria belonging to the order Actinomycetales have proven to be an important source of biologically active and often therapeutically useful natural products. The characterization of orphan biosynthetic gene clusters is an emerging and valuable approach to the discovery of novel small molecules. Analysis of the recently sequenced genome of the thermophilic actinomycete Thermobifida fusca revealed an orphan nonribosomal peptide biosynthetic gene cluster coding for an unknown siderophore natural product. T. fusca is a model organism for the study of thermostable cellulases and is a major degrader of plant cell walls. Here, we report the isolation and structure elucidation of the fuscachelins, siderophore natural products produced by T. fusca. In addition, we report the purification and biochemical characterization of the termination module of the nonribosomal peptide synthetase. Biochemical analysis of adenylation domain specificity supports the assignment of this gene cluster as the producer of the fuscachelin siderophores. The proposed nonribosomal peptide biosynthetic pathway exhibits several atypical features, including a macrocyclizing thioesterase that produces a 10-membered cyclic depsipeptide and a nonlinear assembly line, resulting in the unique heterodimeric architecture of the siderophore natural product.natural product isolation ͉ nonribosomal peptide biosynthesis ͉ genome mining

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“…Five types of siderophores have been isolated: hydroxamates, catecholates, salicylates, nitrosophenols and carboxylates. 7 Some siderophores, such as brasilibactin A, 8 asterobactin, 9 nocobactin NA 10 and nocardamine, 11 are produced by Nocardia spp. In the course of our screening program for biologically active compounds of microbial origin, we isolated a novel heterobactin 12 analog, JBIR-16 (1), containing hydroxamate and catecholate, from the culture broth of Nocardia tenerifensis NBRC 101015 (Figure 1).…”

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confidence: 99%