AUTHOR=Wu Xiu-Yun , Li Tian 

TITLE=A Casein Kinase II Phosphorylation Site in AtYY1 Affects Its Activity, Stability, and Function in the ABA Response

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 8 - 2017

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00323

DOI=10.3389/fpls.2017.00323

ISSN=1664-462X

ABSTRACT=<p>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, <italic>Arabidopsis</italic> 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 <italic>in vitro</italic>, and the S<sup>284</sup> site is the major CKII phosphorylation site. Further analyses indicated that S<sup>284</sup> 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.</p>