Calmodulin isoform-specific activation of a rice calmodulin-binding kinase conferred by only three amino-acids of OsCaM61.
The kinase activity of a Ca(2+)/calmodulin (CaM)-binding serine/threonine protein kinase from rice (Oryza sativa) (OsCBK) has been reported to be unaffected by OsCaM1 binding. In this study, we examined whether other rice CaMs can stimulate OsCBK. It was observed that OsCaM61 stimulated OsCBK in a Ca(2+)-dependent manner. In addition, Ala(111), Gly(123) and Ser(127) were identified as critical residues for OsCBK activation. Mutational study and fluorescent spectroscopy analysis indicated that CaM-binding affinity does not correlate with the kinase activity and that these key amino-acids in OsCaM61 play a vital role in suitable changes of OsCBK conformation for kinase activation.
Li
Dian-Fan
DF
Key Lab of MOE for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Li
Jing
J
Ma
Li
L
Zhang
Lei
L
Lu
Ying-Tang
YT
D000409:Alanine / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation; D005998:Glycine / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000201:enzymology*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012694:Serine / Q000737:chemistry / Q000235:genetics; D013050:Spectrometry, Fluorescence
D002147:Calmodulin; D020033:Protein Isoforms; D012694:Serine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000409:Alanine; D002118:Calcium; D005998:Glycine