Metabolic products of microorganisms

✍ Scribed by G. Winkelmann

• Publisher: Springer
• Year: 1974
• Tongue: English
• Weight: 765 KB
• Volume: 98
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00425266

✦ Synopsis

The transport of ~SFe3+, mediated by various fungal sideramines, was tested using an ornithine-deficient mutant of lqeurospora crassa (arg-5, ota, aga), which can be cultivated completely free of its own sideramines. We have found that Neurospora crassa is able to accumulate iron by its own chelate coprogen (Kin N 20 ~M, Fmax N 1.74 nmol/mg rain) and also by the two exogenous sideramines ferricrocin (Kin N 5 ~M, Vmax N 0.22 nmol/mg rain) and ferrichrysin (Kin N 20 txM, Fm~ ~ 0.4 nmol/mg rain) produced by members of the genus Aspergillus. Other sideramines like ferrichrome, ferriehrome A, and ferrirubin were relatively ineffective as iron transport molecules for this organism. Competitive inhibition of coprogen uptake was observed with all ferriehrome-group compounds: ferrichrysin (K~ ~ 140 ~M), ferrichrome and ferricrocin (K~ ~ 5 ~M). Ferrirubin (K~ ~ 0.5 tzM) was the strongest inhibitor of coprogen uptake in Neurospora crassa.

Inhibition experiments indicate that ferrirubin may possibly block the uptake of coprogen and ferrichrome-type compounds by occupying the receptor sites without being preferably transported. For further characterisation of the coprogen uptake system in Neurospora crassa comparative uptake experiments were performed with the parent wild-type strain 74 A, and with a ferricrocin-produeing Aspergillus [umigatus strain.