ABA and the ubiquitin E3 ligase KEEP ON GOING affect proteolysis of the Arabidopsis thaliana transcription factors ABF1 and ABF3.
Bottom Line: Loss of ABF1 or ABF3 in the keg background has a phenotypic effect similar to the loss of ABI5, and there is no additional rescue of the keg phenotype in abf1 abf3 abi5 keg seedlings.This result suggests that the abundance of other substrates is altered in keg seedlings, affecting growth.In conclusion, ABF1 and ABF3 abundance is affected by ABA and KEG, and the conserved C4 region serves as a stabilizing element.
Affiliation: Department of Molecular and Cellular Biology, UC-Davis, 1 Shields Ave, Davis, CA 95616, USA.Show MeSH
Mentions: Because Myc-ABF1 and Myc-ABF3 degradation was slowed but not eliminated in keg seedlings (Figure 4), we asked whether the keg-independent degradation required the proteasome and was affected by ABA. Both Myc-ABF1 and Myc-ABF3 proteins accumulated in keg seedlings after 6 h of MG132 treatment, indicating Myc-ABF1 and Myc-ABF3 keg-independent degradation is proteasome dependent (Figure 7a,b, keg seedlings immunoblot). In contrast, endogenous ABI5 levels were not affected by proteasome treatment in keg seedlings, in contrast to the strong increase observed in the wild type, as shown in the Myc-ABF3 lines (Figure 7b).
Affiliation: Department of Molecular and Cellular Biology, UC-Davis, 1 Shields Ave, Davis, CA 95616, USA.