Molecular cloning of two novel rice cDNA sequences encoding putative calcium-dependent protein kinases.
We have isolated, from a cDNA library constructed from rice coleoptiles, two sequences, OSCPK2 and OSCPK11, that encode for putative calcium-dependent protein kinase (CDPK) proteins. OSCPK2 and OSCPK11 cDNAs are related to SPK, another gene encoding a rice CDPK that is specifically expressed in developing seeds [20]. OSCPK2 and OSCPK11-predicted protein sequences are 533 and 542 amino acids (aa) long with a corresponding molecular mass of 59436 and 61079 Da respectively. Within their polypeptide chain, they all contain those conserved features that define a plant CDPK; kinase catalytic sequences are linked to a calmodulin-like regulatory domain through a junction region. The calmodulin-like regulatory domain of the predicted OSCPK2 protein contains 4 EF-hand calcium-binding sites while OSCPK11 has conserved just one canonical EF-hand motif. In addition, OSCPK2- and OSCPK11-predicted proteins contain, at their N-terminal region preceding the catalytic domain, a stretch of 80 or 74 residues highly rich in hydrophilic amino acids. Comparison of the NH2-terminal sequence of all three rice CDPKs so far identified (OSCPK2, OSCPK11 and SPK) indicates the presence of a conserved MGxxC(S/Q)xxT motif that may define a consensus signal for N-myristoylation. OSCPK2 and OSCPK11 proteins are both encoded by a single-copy gene and their polyadenylated transcripts are 2.4 and 3.5 kb long respectively. OSCPK2 and OSCPK11 mRNAs are equally abundant in rice roots and coleoptiles. A 12 h white light treatment of the coleoptiles reduces the amount of OSCPK2 mRNA with only a slight effect on the level of OSCPK11 transcript. With anoxic treatments, OSCPK2 mRNA level declined significantly and promptly while the amount of OSCPK11 transcript remained constant.
Breviario
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Istituto Biosintesi Vegetali, C.N.R., Milan, Italy.
Morello
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Giani
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D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D018548:Cotyledon; D018744:DNA, Plant / Q000737:chemistry / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D011494:Protein Kinases / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D017871:Calcium-Calmodulin-Dependent Protein Kinases
D018744:DNA, Plant; D009838:Oligodeoxyribonucleotides; D011494:Protein Kinases; D012333:RNA, Messenger; D017871:Calcium-Calmodulin-Dependent Protein Kinases