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: Wild-type or keg seedlings expressing Myc-ABF1 or Myc-ABF3 were also treated with ABA. Myc-ABF1 increased after 6 h of ABA treatment in the wild type, as observed previously (Figure 2), but this was not consistently the case in keg seedlings (Figure 8a). For Myc-ABF3, transgenic lines A and B accumulated slightly more Myc-ABF3 protein in ABA-treated keg seedlings compared with control keg seedlings, but two other lines did not (line C, Figure 8b, and line D, not shown). Endogenous ABI5 strongly accumulated with ABA treatment in wild-type seedlings, indicating that the ABA response was functional in these seedlings at this developmental stage. In keg seedlings, ABI5 levels were high without ABA, and increased slightly with ABA (Figure 8b).
Affiliation: Department of Molecular and Cellular Biology, UC-Davis, 1 Shields Ave, Davis, CA 95616, USA.