Figure 1

Ferrichrome induces the growth of leucine-auxotrophic cells on high ammonium media. (A) Chemical structures of ferrichrome and (R,Z)-10-hydroxyoctadec-8-enoic acid (used as an NSF in this study). (B) Adaptive growth of leucine-auxotrophic leu1-32 cells by wild-type inoculation or chemicals. A cell suspension of the leu1-32 strain was spotted on a variety of EMM plates containing 0.5%, 1.0% or 2.0% NH₄Cl and 0.2 mM of leucine as nitrogen sources. Wild-type cell suspension (3 μl of a 0.2 OD₅₉₅ suspension), cell extract (3 μl of a 250 μg/ml extract), NSF (150 ng in 3 μl 50% MeOH) or ferrichrome (150 ng in 3 μl of 50% MeOH) was spotted to the left of the five spots of leu1-32 cells. Representative images from three independent experiments are shown. (C) Wild-type or sib1Δ cells were used as an inducer strain. Cells were incubated on EMM containing 2.0% NH₄Cl and leucine, supplemented with dipyridyl (100 μM). Dipyridiyl was added to induce production of ferrichome.