Figure 1.
Rescue of aco1 yeast from glutamate auxotrophy by expression of S138 IRP1 mutants. Yeast expressing either wild type (WT) or S138 (S138A, S138D, or S138E) IRP1 mutants were grown overnight in SD-Ura, washed twice with sterile H2O, and suspended into SD-Ura lacking glutamate. Nontransformed yeast (0615d) were grown in SD supplemented with uracil. Ten microliters containing between 2 × 105 and 2 × 102 yeast cells were spotted onto agar plates containing SD supplemented with uracil with or without glutamate as indicated. Growth after 4 days is shown. Columns 1 and 5, 2 × 105 cells; columns 2 and 6, 2 × 104 cells; columns 3 and 7, 2 × 103 cells; columns 4 and 8, 2 × 102 cells. (a) Aerobic growth. (b) Effect of anaerobiosis on growth of aco1 yeast expressing S138 IRP1 mutants on glutamate-free media. Growth analysis was performed as described above except that plates were incubated in an anaerobic chamber.