PLANT PHYSIOLOGY , Vol 112, Issue 1 259-264, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Regulation of De-N-Glycosylation Enzymes in Germinating Radish Seeds
S. Berger, A. Menudier, R. Julien and Y. Karamanos
Institut de Biotechnologie, Universite de Limoges, 123 Avenue Albert Thomas, 87060 Limoges Cedex, France
The activities of the de-N-glycosylation enzymes endo-N-acetyl-
[beta]-D-glucosaminidase (ENGase; EC 3.2.1.96) and peptide-N4-
(N-acetyl-[beta]-D-glucosaminyl) asparagine amidase (PNGase; EC 3.5.1.52)
were monitored during germination and postgerminative development in radish
(Raphanus sativus L. cv Flamboyant). The ENGase activity was detected only
during postgermination, whereas the PNGase activity was present at high
levels in both stages. When germination was inhibited with abscisic acid or
cycloheximide, PNGase activity was detected at a basic level and ENGase
activity was not detected at all. PNGase is present as an active protein in
dry seeds and is apparently synthesized during seed formation. Conversely,
the absence of ENGase in dry seeds suggests that its activity is dependent
on the protein synthesis that occurs during and after germination.
Treatment with gibberellic acid confirmed the production of both
de-N-glycosylation enzymes after germination, and demonstrated a temporal
delay between the production of the two enzymes during this period. Our
results suggest that the two de-N-glycosylation enzymes are differentially
regulated during plant development.
