Plant Molecular Biology 52: 1191–1202, 2003.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
Isolation and characterization of a novel rice Ca
kinase gene involved in responses to diverse signals including cold, light,
cytokinins, sugars and salts
, Jung-Sook Lee
, Seung Ah Choi
, Seung Joo Go
and In Sun
Department of Molecular Physiology, National Institute of Agricultural Biotechnology, Suweon 441-707, Korea
author for correspondence; e-mail firstname.lastname@example.org or email@example.com);
Department of Molecu-
lar Biology, Sejong University, Seoul 143-747, Korea;
Department of Bioinformatics, National Institute of
Agricultural Biotechnology, Suweon 441-707, Korea;
these authors contributed equally to this work
Received 7 March 2003; accepted in revised form 8 July 2003
Key words: calcium signaling, CIPK/PKS, cold response, OsCK1, rice
We have isolated a cold-inducible gene (designated OsCK1) from Oryza sativa by a differential cDNA screening
technique. Sequence analysis indicated that the open reading frame of the OsCK1 gene consists of 1350 bp en-
coding 449 amino acid residues, which is very similar to a family of calcineurin B-like protein (CBL)-interacting
protein kinases (CIPKs) or salt overly sensitive 2 (SOS2)-like protein kinases (PKS) in Arabidopsis. CIPKs/PKS
are a group of Ser/Thr protein kinases associated with the AtCBL/SOS3-like calcium-binding proteins (SCaBP).
OsCK1 actually interacts with AtCBL3 through the C-terminal region in a yeast two-hybrid system, suggesting
that OsCK1 is probably a rice orthologue of one of the CIPK/PKS members. Expression of the OsCK1 gene
was detected mainly in the shoots and highly inducible by diverse signals such as cold, light, salt, sugar and
cytokinins. In addition, calcium increased the OsCK1 transcript level, whereas a calcium ionophore, A23187,
partially abolished stimulus-induced expressions. OsCK1 phosphorylated itself and a generic substrate, myelin
basic protein, in the preference of Mn
. Deletion of the C-terminal region from OsCK1 signiﬁcantly decreased
autophosphorylation activity without affecting the ability for substrate phosphorylation. These ﬁndings suggest
that the CBL/CIPK or SCaBP/PKS signaling pathways recently found in Arabidopsis mayalsoexistinriceand
function in cold response in which calcium signal serves as a second messenger.
Abbreviations: CBL, calcineurin B-like protein; CIPK, CBL-interacting protein kinase; PKS, SOS2-like protein
kinase; SCaBP, SOS3-like calcium-binding protein; SOS, salt overly sensitive; GST, glutathione S-transferase;
SNF1, sucrose non-fermenting protein kinase; SnRK, SNF1-related protein kinase; TBS, Tris-based saline buffer
Calcium signaling has been implicated in cold re-
sponse and acclimation of a plant. Cold shock eli-
cits a transient rise in cytosolic calcium concentra-
tion (Knight et al., 1996) and the calcium signature
is critical for the induction of several cold-induced
genes (Monroy et al., 1995; Tahtiharju et al., 1997).
Plant cold response is also associated with the rapid
changes in the protein phosphorylationstatus triggered
by calcium signature (Monroy et al., 1993, 1998).
Therefore, it appears that a calcium-dependent, pro-
tein phosphorylation-mediated pathway participates
in cold signal transduction. Calcium-binding proteins
may couple the calcium signal to downstream events.
Previous pharmacological studies predict calmodulin
and CDPKs as such coupling molecules (Monroy and
Dhindsa, 1995; Tahtiharju et al., 1997). Transcrip-