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Sucrose induces rapid activation of CfSAPK, a mitogen‐activated protein kinase, in Cephalostachyum fuchsianum Gamble cells
Author(s) -
LI LUBIN,
LI YUAN,
ZHANG LU,
XU CHUNHUI,
SU TONGBING,
REN DONGTAO,
YANG HAILIAN
Publication year - 2012
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02500.x
Subject(s) - kinase , biochemistry , protein kinase a , phosphatase , complementary dna , phosphorylation , serine , biology , c raf , threonine , sucrose , map2k7 , microbiology and biotechnology , cyclin dependent kinase 2 , gene
Sucrose was recently demonstrated to function as a molecular signal. However, sucrose‐specific sensing and signalling pathways remain largely undefined. Here, we show that Cephalostachyum fuchsianum sucrose‐activated protein kinase (CfSAPK) is transiently and specifically activated by sucrose in C. fuchsianum Gamble suspension cells. The result suggested that CfSAPK participates in a sucrose‐signalling pathway. CfSAPK was partially purified from sucrose‐treated cells and further analysed. Kinase activity assays revealed that CfSAPK preferentially used myelin basic protein (MBP) as substrate in vitro and strongly phosphorylate MBP threonine residue(s) and weakly phosphorylated MBP serine residue(s). Of the divalent cations tested, Mg 2+ was required for CfSAPK activation. Phosphatase treatment of CfSAPK abolished its kinase activity, indicating that phosphorylation is required for CfSAPK activation. Seven internal tryptic peptides identified from CfSAPK matched mitogen‐activated protein kinases (MAPKs) in plants. CfSAPK cDNA was cloned using RT‐PCR and rapid amplification of cDNA ends (RACE). CfSAPK cDNA encodes a 382‐amino acid protein with a calculated molecular mass of 43 466.9 Da. The CfSAPK protein contains all 11 conserved kinase subdomains found in other Ser/Thr kinases. The amino acids sequence of CfSAPK is highly homologous to group A MAPKs in monocotyledon plants.