Figure 6.

The citrus Ubc13 and ubiquitin‐conjugating enzyme variant (Uev) proteins complement yeast Δubc13 and Δmms2/uev1a mutants. (A) The Citrus sinensis Ubc13 and Uev genes under the control of a copper‐induced promoter were expressed in the yeast mutants Δubc13 and Δmms2/uev1a as glutathione transferase (GST) fusions. The proteins (43 kDa) were induced with 0.5 mm copper sulphate for 2 h, purified by affinity chromatography and probed with anti‐GST serum. Induced (I) and noninduced (NI) samples are shown. The amounts of protein loaded on the gels are shown in Fig. S2 (see Supporting Information). (B) Growth of the yeast strain SUB62 and its derivative mutants Δubc13 and Δmms2/uev1a in synthetic complete (SC) medium in the presence of increasing amounts of methylmethanesulphonate (MMS). The growth of both mutants in MMS gradient plates can be rescued by the corresponding citrus Ubc13 and Uev genes.