INVESTIGADORES
SALERNO Graciela Lidia
artículos
Título:
A CDPK type protein kinase is involved in rice SPS light modulation.
Autor/es:
G.C. PAGNUSSAT; D.F. FIOL; G.L. SALERNO
Revista:
PHYSIOLOGIA PLANTARUM
Editorial:
Munksgaard International Publishers Ltd
Referencias:
Lugar: Copenhagen, Denmark ; Año: 2002 vol. 115 p. 183 - 189
ISSN:
0031-9317
Resumen:
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A protein kinase activity that can phosphorylate and inactivate rice (Oryza sativa) sucrose-phosphate synthase (SPS; UDP-glucose: D-fructose-6-phosphate-2-glucosyl transferase, EC 2.4.1.14) was measured in extracts prepared from leaves exposed to light-dark transitions. Enzyme activity present in extracts from dark leaves was about 5-fold higher than the activity in extracts from leaves that had been collected in the light. The protein kinase (named R-SPSK) was purified about 100-fold from dark leaves and its biochemical properties were studied. The micromolar dependence of Ca2+ exhibited by R-SPSK, and its response to calmodulin antagonists were similar to the properties associated with members of the plant Calcium-Dependent Protein Kinase (CDPK) family. Two modulators of SPS activity, Pi and Glc-6-P, were examined for an effect on R-SPSK. While Glc-6-P did not affect R-SPSK activity, Pi drastically increased the kinase activity. Taken together, these data provide evidence that SPS may be regulated by a CDPK type protein-kinase whose activity is modulated by light-dark transitions and stimulated by Pi, the negative effector of SPS activity.
