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ABA and the ubiquitin E3 ligase KEEP ON GOING affect proteolysis of the A rabidopsis thaliana transcription factors ABF 1 and ABF 3
Author(s) -
Chen YiTze,
Liu Hongxia,
Stone Sophia,
Callis Judy
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12259
Subject(s) - ubiquitin ligase , proteolysis , transcription factor , microbiology and biotechnology , ubiquitin , proteasome , biology , biochemistry , chemistry , gene , enzyme
Summary The ABA Binding Factor/ABA‐Responsive Element Binding Proteins (ABF/AREB) subfamily of b ZIP ‐type transcription factors are positive effectors of ABA responses. Here, we examine the proteolytic regulation of two members: A rabidopsis thaliana ABF 1 and ABF 3. Both transcription factors are unstable in seedlings, and their degradation is sensitive to proteasome inhibition. ABA treatment of seedlings leads to their rapid accumulation, the result of slowed proteolysis. Deletion of the conserved C–terminal region required for 14–3–3 interaction destabilizes the proteins. The degradation of ABF 1 and ABF 3 are slower in vivo in seedlings lacking the ubiquitin E3 ligase KEEP ON GOING ( KEG ), and in vitro in extracts from keg seedlings, implicating KEG in their degradation. ABF 1 and ABF 3 are ubiquitylation substrates of KEG in vitro , and in vitro pull‐down assays document their direct interaction. In contrast to ABI 5, another KEG substrate, the degradation of ABF s and proteolytic regulation of ABF s by ABA still occurs in keg seedlings, suggesting that additional E3s participate in ABF 1 and ABF 3 proteolysis. Loss of ABF 1 or ABF 3 in the keg background has a phenotypic effect similar to the loss of ABI 5, 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, ABF 1 and ABF 3 abundance is affected by ABA and KEG , and the conserved C4 region serves as a stabilizing element.