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Diverse phosphoregulatory mechanisms controlling cyclin‐dependent kinase‐activating kinases in Arabidopsis
Author(s) -
Shimotohno Akie,
Ohno Ryoko,
Bisova Katerina,
Sakaguchi Norihiro,
Huang Jirong,
Koncz Csaba,
Uchimiya Hirofumi,
Umeda Masaaki
Publication year - 2006
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/j.1365-313x.2006.02820.x
Subject(s) - arabidopsis , kinase , microbiology and biotechnology , cyclin dependent kinase , cyclin , chemistry , biology , computational biology , biochemistry , cell cycle , gene , mutant
Summary For the full activation of cyclin‐dependent kinases (CDKs), not only cyclin binding but also phosphorylation of a threonine (Thr) residue within the T‐loop is required. This phosphorylation is catalyzed by CDK‐activating kinases (CAKs). In Arabidopsis three D‐type CDK genes ( CDKD;1 – CDKD;3 ) encode vertebrate‐type CAK orthologues, of which CDKD;2 exhibits high phosphorylation activity towards the carboxy‐terminal domain (CTD) of the largest subunit of RNA polymerase II. Here, we show that CDKD;2 forms a stable complex with cyclin H and is downregulated by the phosphorylation of the ATP‐binding site by WEE1 kinase. A knockout mutant of CDKD;3 , which has a higher CDK kinase activity, displayed no defect in plant development. Instead, another type of CAK – CDKF;1 – exhibited significant activity towards CDKA;1 in Arabidopsis root protoplasts, and the activity was dependent on the T‐loop phosphorylation of CDKF;1. We propose that two distinct types of CAK, namely CDKF;1 and CDKD;2, play a major role in CDK and CTD phosphorylation, respectively, in Arabidopsis.