RESUMO
A novel trishydroxamate siderophore, named basidiochrome, was isolated as the principal siderophore from low-iron culture filtrates of Ceratobasidium and Rhizoctonia species which are known as mycorrhizal fungi associated with orchid roots. Ion-exchange chromatography and preparative HPLC yielded a pure compound which contained two components according to GC-MS analysis: L: -N(5)-hydroxy-ornithine and 3-methyl-2-cis-pentenedioic acid (3-methyl-cis-glutaconic acid). FTICR-ESI-MS of both the iron-free and ferric form indicated an elemental composition of C(33)H(47)N(6)O(16)Fe (MW = 839) for the ferric form of basidiochrome. The connectivity was further elucidated by 2D-NMR techniques (HSQC, HMBC, COSY, NOESY) indicating that basidiochrome is a novel linear tripeptide consisting of three L: -N(5)-hydroxy-ornithines each linked to 3-methyl-2-cis-pentenedioic acid residues.
