AtMTM1 and AtMTM2 are functional homologs of yMTM1
To analyze the complementary effect of AtMTM1 and AtMTM2 for yMTM1 in yeast MnSOD activation, we transformed AtMTM1 and AtMTM2in yMTM1 -mutant (ymtm1Δ ) cells (Figure 2) .
Yeast wild-type (WT) cells contained one activity band for CuZnSOD (ySOD1) and two bands for MnSOD (ySOD2) and residual ySOD2 activities remained in ymtm1Δ cells (Figure 2, lanes 1, 2) , as reported earlier (Luk et al., 2003). We showed ySOD2 activities were recovered when ymtm1Δ cells were transformed with AtMTM1or AtMTM2 (Figure 2, lanes 3, 4) , indicating AtMTM1 and AtMTM2 are functional homologs of yMTM1. Moreover, the ySOD2 activities were not increased by co-transformation of AtMTM1 andAtMTM2 (Figure 2, lane 5) , implying the synergistic effect did not occur in ymtm1Δ cells.
In conclusion, AtMTM1 and AtMTM2 transformations recovered ySOD2 activities in ymtm1Δ cells, which was similar toyMTM1 transformation (Supplemental Figure S4) , indicating they shared similar ability for ySOD2 activation.