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: We next used the cell-free degradation assay to determine whether ABF1 or ABF3 degradation is slowed in keg extracts in vitro, as previously observed in vivo. The equivalent in vitro proteolysis of GST-FUSCA3, a B3 domain-containing transcription factor involved in embryogenesis previously demonstrated to be unstable (Lu et al., 2010), in wild-type and keg extracts demonstrates active proteolysis in keg extracts (Figure 5a). In wild-type protein extracts, 12% of His-Flag-ABF1 (Figure 5b, lane 4) or 2% of His-Flag-ABF3 (Figure 5c, lane 4) remained after 90 or 20 min, respectively, whereas 87 and 87%, of His-Flag-ABF1 and His-Flag-ABF3, respectively, remained in keg extracts (Figure 5b,c, lanes 8). The slower in vivo (Figure 4) and in vitro (Figure 5) degradation of tagged ABF1 and ABF3 in keg indicates ABF1 and ABF3 degradation is modulated by KEG E3 ligase.
Affiliation: Department of Molecular and Cellular Biology, UC-Davis, 1 Shields Ave, Davis, CA 95616, USA.