Ocean siderophore

Deng J, Hamada Y, Shioiri T (1995) Total Synthesis of Alterobactin A, a Super Siderophore from an Open-Ocean Bacterium. J Am Chem Soc 117 7824... 

While specific compounds such as siderophores have been found in natural waters, the bulk of the dissolved organic matter (DOM) is made up of relatively refractory compounds known as humic substances. These substances exhibit complex, ill-defined structures with the actual structure depending markedly on the source of the organic material. DOM in the open ocean is almost entirely authochthonous and formed by condensation, polymerisation and partial oxidation of smaller molecules such as triglycerides, sugars and amino acids and exhibits very little aromatic character [78]. In contrast, the DOM in fresh and coastal waters is largely allochthonous and derived... 

Figure 38 5 Short term Fe uptake rates from model iron/ligand complexes hy Trichodesmium colonies collected in the suhtropical Atlantic Ocean. Shown are uptake rates from Fe complexed to a trihydroxamate siderophore (desferrioxamine), a dihydroxamate siderophore (rhodoturulic acid), and a porphyrin (protoporphyrin IX). For comparative purposes, uptake rates were also measured using added inorganic Fe (111). Achilles et al. (2003), Limnology and Oceanography 48 2250-2255.

Consistent with the role of iron as a limiting nutrient in EINLC systems is the notion that organisms may have evolved competitive mechanisms to increase iron solubility and uptake. In terrestrial systems this is accomplished using extracellularly excreted or membrane-bound siderophores. Similar compounds have been shown to exist in sea water where the competition for iron may be as fierce as it is on land. In open ocean systems where it has been measured, iron-binding ligand production increases with the... 

Alterobactin, a 19-membered macrocydic depsipeptide containing two types of unusual building block, two i-threo- -hydroxyaspartic acids and one (3S,4S)-4,8-diamino-3-hydroxyoctanic acid attached to a catechol carboxylate at the N -site. It was isolated from a open-ocean bacterium M-teromonas luteoviolacea coUected off Chub Cay, Bahamas. Alterobadin is a depsipeptide siderophore exhibiting extraordinary affinity for ferric ion. The total synthesis has been described [R. T. Reid et al.. Nature 1993, 366, 455 J. Deng et al.. Synthesis 1998, 627]. 

Although siderophores secreted by terrestrial microorganisms comprise the vast majority of studies, recent experiments indicating that low ocean iron concentrations limit the growth of marine microorganisms have increased interest in marine siderophores (Figure ulk of... 

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