Regulation of sucrose-sucrose-fructosyltransferase in barley leaves

• Published in: Plant physiology (Bethesda) Vol. 97; no. 2; pp. 811 - 813
• Main Authors: David M. Obenland, Urs Simmen, Boller, Thomas, Wiemken, Andres
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-10-1991
• Subjects: actividad enzimatica; activite enzymatique; Barley; Biological and medical sciences; Biosynthesis; cicloheximida; Communications; cycloheximide; enzyme inhibitors; Enzymes; enzymic activity; feuille; Fructans; fructosa; fructose; Fundamental and applied biological sciences. Psychology; hojas; hordeum vulgare; inhibidores de enzimas; inhibiteur d' enzyme; Leaves; light; lumiere; luz; Metabolism; Photons; Physiological regulation; Plant physiology and development; Plants; proteasas; protease; proteases; Protein synthesis; proteolisis; proteolyse; proteolysis; saccharose; sucrosa; sucrose; transferasas; transferase; transferases; Vacuoles; Monocotyledones; Regulation(control); Enzymatic activity; Hordeum vulgare; Enzyme; Gramineae; Angiospermae; Spermatophyta; Plant leaf; Cereal crop; Sucrose 1F-fructosyltransferase
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.97.2.811

The activity of sucrose-sucrose-fructosyltransferase (SST), a vacuolar enzyme strongly induced by light in excised leaves of barley (Hordeum vulgare L.), rapidly declined even in continuous light upon feeding of cycloheximide (CHI). The rate of decline was similar to that observed in light-treated leaves that were placed into darkness, in the presence or absence of CHI. The protease inhibitor leupeptin totally stopped the decline in SST activity in the dark and caused a substantial increase in the rate of induction of SST activity by light. Feeding of sucrose prevented or even reversed the SST activity decay induced by darkness in the absence of CHI but did not stabilize SST activity in the presence of CHI. The results suggest that SST is continuously subjected to rapid, constant proteolytic degradation in the vacuole, and that the enhancement of SST activity in the light or upon feeding sucrose in the dark is due exclusively to de novo protein synthesis.