M. A. F. Jalal

Siderophore Mediated Iron(III) Uptake in Gliocladium virens: 1. Properties of cis-Fusarinine, trans-Fusarmine, Dimerum Acid, and Their Ferric Complexes

Gliocladium virens (ATCC 24290) produces two monohydroxamates (cis- and trans-fusarinine) and a dihydroxamate (dimerum acid) as the major siderophores in the culture filtrate. This fungus also produces minor quantities of three trihydroxamates (the deferri forms of ferricrocin, coprogen B, and coprogen). Structural features of the free ligands and the metal complexed forms of cis-fusarinine (cF), trans-fusarinine (tF), and dimerum acid (DA) have been investigated using electronic (visible), circular dichroism (CD), and NMR spectroscopy. In aqueous solution, in the pH range of 6.5-8.0, all of the ferric complexes of cF (and tF) exist as 3:1 chelates. Fe(cF)3 [or Fe(tF)3] forms both lambda and delta coordination isomers, but the former in a slight excess. DA forms a 3:2 ferric complex in the pH range of 5.0-8.0. Iron coordination in Fe2(DA)3 is predominantly delta. DA ligands in Ga2(DA)3 exist as two different conformers at a ratio of 2:1. In mixed solution cF, tF, and DA form a large number of homogeneous and heterogeneous Fe(III) chelates.

Purification and crystallization of ferric enterobactin receptor protein, FepA, from the outer membranes of Escherichia coli UT5600/pBB2

The ferric enterobactin receptor protein, FepA, was isolated and purified from the outer membranes of a genetically transformed strain of Escherichia coli (UT5600/pBB2) using anion‐exchange chromatography, chromatofocusing and gel filtration. The purified protein was found to crystallize from 25 mM sodium phosphate buffer in the presence of 0.8% β‐D‐octylglucoside under a range of conditions. The protein formed mostly small rods and needle‐shaped crystals in the hanging drop method.

Separation of ferrichromes and other hydroxamate siderophores of fungal origin by reversed-phase chromatography

Iron(III) chelates of nineteen trihydroxamate siderophores of fungal origin, including ferrichromes, coprogen and triacetylfusarinine C, were separated on a preparative scale with a reversed-phase column using the octadecyl silica gels LRP-1 or LRP-2 as the stationary phase and a water-methanol gradient as the mobile phase. Using this system in combination with silica gel column chromatography, most siderophores can be obtained in pure form. Factors affecting the mobility of these compounds in the reversed-phase system are discussed.

Nα-Dimethylcoprogens Three novel trihydroxamate siderophores from pathogenic fungi

SummaryThree novel siderophores have been isolated from a highly pathogenic strain ofAlternaria longipes (ATCC 26293). The compounds are Nα-dimethylated analogs of coprogen, neocoprogen I and isoneocoprogen I. Structures of the compounds have been determined by1H- and13C-NMR, fast-atom-bombardment (FAB) mass spectroscopy and partial hydrolysis. One of the new compounds, Nα -dimethylcoprogen, is also produced, as the major siderophore, in another fungus,Fusarium dimerum.

Siderophore mediated iron(III) uptake in Gliocladium virens. 2. Role of ferric mono- and dihydroxamates as iron transport agents

The Fe(III) transport properties of the monohydroxamates, cis-fusarinine (cF) and trans-fusarinine (tF), and the dihydroxamate, dimerum acid (DA), the major siderophores of the fungus, Gliocladium virens ATCC 24290, have been investigated using labeled ferric siderophores. Fe(cF)3, Fe(tF)3 and Fe2(DA)3 (and also one of the minor trihydroxamates, ferricrocin) transport extracellular 55Fe(III) very efficiently into the fungus. Coprogen, another minor trihydroxamate, behaves as a weak Fe(III)-transporting agent. The respiratory poisons, KCN and NaN3, significantly inhibit uptake activity, indicating that the Fe(III) uptake mediated by Fe(cF)3, Fe(tF)3, and Fe2(DA)3 involves active transport systems in the membrane. A number of fungal species, both producers and nonproducers of cF, tF, and DA, show ability at varying degrees to transport 55Fe(III) bound to these siderophores.

Siderophores of highly phytopathogenic Alternaria longipes. Structures of hydroxycoprogens.

SummaryAlternaria longipes ATCC 26293, a highly phytopathogenic fungus, has been found to produce a large number of siderophores under iron-deficient conditions. Most of the compounds are members of the coprogen family. Structures of three novel siderophores, termed hydroxycoprogens, have been determined by1H and13C NMR, FAB mass spectrometry and partial hydrolysis. The compounds are analogs of coprogen, neocoprogen I and isoneocoprogen I, in which one of the terminaltrans-anhydromevalonic acid residues is replaced by atrans-4,5 dihydroxy-3-methyl-2-pentenoic acid residue.Alternaria longipes ATCC 26293, a highly phytopathogenic fungus, has been found to produce a large number of siderophores under iron-deficient conditions. Most of the compounds are members of the coprogen family. Structures of three novel siderophores, termed hydroxycoprogens, have been determined by 1H and 13C NMR, FAB mass spectrometry and partial hydrolysis. The compounds are analogs of coprogen, neocoprogen I and isoneocoprogen I, in which one of the terminal trans-anhydromevalonic acid residues is replaced by a trans-4,5 dihydroxy-3-methyl-2-pentenoic acid residue.

Crystal structure of retro-isomer of the siderophore ferrioxamine E

AbstractThe structure of the retro-isomer of ferrioxamine E sesqui-hydrate, a ferrioxamine E analog in which the N-hydroxy and carbonyl functions are transposed, was found to be isomorphous with that of ferrioxamine E. The interchange of N and C atoms in the three hydroxamate groups seemed to have caused some noticeable differences in the iron-coordination octahedron. The difference in the average Fe–O(N) and Fe–O(C) distances in the retro-isomer, 0.061Å, is about one-half of that observed in case of ferrioxamine E, 0.102Å. The ligand bite of the two complexes is similar (1.27), the retro-isomer has a smaller (42°) twist angle than that (45°) of ferrioxamine E. Crystal data: C27H45N6O9Fe·1.5H2O, triclinic,

Formation of Ent-isophleichrome by Cladosporium herbarum Isolated from Sugar Beet

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