Abstract
The phosphorylation and dephosphorylation of proteins are crucial in the regulation of protein activity and stability in various signaling pathways. In this study, we identified an ABA repressor, Arabidopsis Ying Yang 1 (AtYY1) as a potential target of casein kinase II (CKII). AtYY1 physically interacts with two regulatory subunits of CKII, CKB3, and CKB4. Moreover, AtYY1 can be phosphorylated by CKII in vitro, and the S284 site is the major CKII phosphorylation site. Further analyses indicated that S284 phosphorylation can enhance the transcriptional activity and protein stability of AtYY1 and hence strengthen the effect of AtYY1 as a negative regulator in the ABA response. Our study provides novel insights into the regulatory mechanism of AtYY1 mediated by CKII phosphorylation.
Highlights
Mammalian Yin Yang 1 (YY1) is an evolutionarily conserved Cys2/His2 (C2H2) zinc-finger transcription factor that has a fundamental role in various biological processes including cell growth, cell differentiation, embryonic development and tumorigenesis (Zhang et al, 2011)
Sequence analysis1 revealed that the DDGS284DQD sequence of AtYY1 is a predicted casein kinase II (CKII) phosphorylation site and is highly similar to a reported mammalian YY1 CKII phosphorylation
To confirm the hypothesis that AtYY1 is a target of CKII, we first tested whether AtYY1 can interact with CKII subunits
Summary
Mammalian Yin Yang 1 (YY1) is an evolutionarily conserved Cys2/His (C2H2) zinc-finger transcription factor that has a fundamental role in various biological processes including cell growth, cell differentiation, embryonic development and tumorigenesis (Zhang et al, 2011). Plant YY1 shows structural similarity with mammalian YY1 protein, which contains four conserved tandem C2H2 zinc fingers (Xu et al, 2001; Li et al, 2016). Arabidopsis YY1 (AtYY1) can bind to a conserved YY1 binding site and has both repression and activation domains (Li et al, 2016). To date, increasing evidence demonstrates that plant YY1 is involved in the regulation of multiple developmental and physiological processes, e.g., hormone responses, photosynthesis and fungal resistance (Xu et al, 2001; Lai et al, 2013; Li et al, 2016). AtYY1 can act as a repressor in ABA signaling by directly upregulating ABA REPRESSOR1 (ABR1) expression, in addition to negatively regulating ABA-responsive gene expression (Li et al, 2016)
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