Fig. 1.

Yeast Mms19 is a CIA component acting late in cytosolic Fe/S protein maturation. (A) ⁵⁵Fe incorporation into cytosolic Fe/S proteins. Gal-GFP-MMS19 yeast cells producing Rli1-HA, Ntg2-HA or Met10-HA were grown in minimal medium (SC) containing galactose (Gal) or glucose (Glc). After radiolabeling with ⁵⁵Fe, cell extracts were analyzed for the indicated Fe/S proteins by immunoblotting, and associated ⁵⁵Fe was quantified by immunoprecipitation and scintillation counting. (B) Enzyme activities of the cytosolic Fe/S proteins isopropylmalate isomerase (Leu1) and sulfite reductase (SiR), and of alcohol dehydrogenase (ADH) were measured in extracts of indicated cells grown for 36 h in glucose-containing SC and plotted relative to wild-type cell activities. (C) SiR activity was measured in wild-type (WT) and Δmms19 cells without and with a Mms19-encoding plasmid on SC (SC-Bi) or YP glucose plates containing bismuth ammonium citrate and sodium sulfite. Sulfide produced by SiR after growth for 3 days yields Bi₂S₃ (brown precipitate). (D) Mms19 acts late in biogenesis. ⁵⁵Fe incorporation into the indicated CIA proteins was measured as in (A) for Gal-GFP-MMS19 cells with plasmids encoding Cfd1-TAP and Nbp35-TAP.