Rice SPK, a Calmodulin-Like Domain Protein Kinase, Is Required for Storage Product Accumulation during Seed Development: Phosphorylation of Sucrose Synthase Is a Possible Factor

AUTOR(ES)

Asano, Takayuki

FONTE

American Society of Plant Biologists

RESUMO

Suc, an end product of photosynthesis, is metabolized by Suc synthase in sink organs as an initial step in the biosynthesis of storage products. Suc synthase activity is known to be regulated by reversible phosphorylation, but the details of this process are unclear at present. Rice SPK, a calcium-dependent protein kinase, is expressed uniquely in the endosperm of immature seed, and its involvement in the biosynthetic pathways of storage products was suggested. Antisense SPK transformants lacked the ability to accumulate storage products such as starch, but produced watery seed with a large amount of Suc instead, as the result of an inhibition of Suc degradation. Analysis of in vitro phosphorylation indicated that SPK phosphorylated specifically a Ser residue in Suc synthase that has been shown to be important for its activity in the degradation of Suc. This finding suggests that SPK is involved in the activation of Suc synthase. It appears that SPK is a Suc synthase kinase that may be important for supplying substrates for the biosynthesis of storage products.

Documentos Relacionados

• An axoplasmic myosin with a calmodulin-like light chain.
• A C-terminal, calmodulin-like regulatory domain from the plasma membrane Ca2+-pumping ATPase.
• Isolation and characterization of a calmodulin-like protein from Halobacterium salinarium.
• Stimulation of Ca2+-dependent neurotransmitter release and presynaptic nerve terminal protein phosphorylation by calmodulin and a calmodulin-like protein isolated from synaptic vesicles
• Isolation, sequencing, and analysis of a calmodulin-like cDNA from pea (Pisum sativum L. var Alaska).