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

Abstract

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 Fe 2(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 NaN 3, significantly inhibit uptake activity, indicating that the Fe(III) uptake mediated by Fe(cF) 3, Fe(tF) 3, and Fe 2(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.