Figure 1.

The F-box of Mdm30p is required for mitochondrial fusion and respiration as well as degradation of Fzo1p. (A) Typical images of fused (green), tubular (yellow), fizzed (red), and aggregated (blue) mitochondria quantified in Figures 1C and Supplemental Data Table S2. (B) Amino acids 19, 20, 22, and 23 conserved in F-box motifs were mutated as indicated in Mdm30-HA to yield the fbox-HA mutant. (C) Mitochondrial morphology was assessed in wild-type (vector; W303 background), mdm30Δ (vector), or mdm30Δ cells expressing either Mdm30-HA or an F-box mutant of Mdm30-HA (fbox-HA) under control of the TEF promoter. (D) The same strains as described in C were grown at 37°C on selective media containing either dextrose or glycerol as the only carbon source. (E) Rate of Fzo1p degradation was analyzed in the indicated strains (W303 background) after shift to 37°C and treatment with CHX. Yeast extracts were prepared at the indicated times and remaining Fzo1p or Mdm30-HA evaluated by immunoblotting. Levels of a stable protein, phosphoglucokinase (PGK), are shown as a loading control.