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Sucrose‐phosphate synthase in tree species: light/dark regulation involves a component of protein turnover in Prosopis juliflora (SW DC)
Author(s) -
Sinha Alok K.,
Shirke P. A.,
Pathre Uday,
Sane P. V.
Publication year - 1997
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549700204211
Subject(s) - cycloheximide , chloroplast , sucrose phosphate synthase , biology , atp synthase , protein turnover , protein biosynthesis , prosopis , photosynthesis , biochemistry , spinach , botany , sucrose , chemistry , enzyme , sucrose synthase , gene , invertase
Light dependent modulation of sucrose‐phosphate synthase activity (SPS; EC 2.4.1.14) was studied in a tree species, namely Prosopis juliflora. In this paper we demonstrate that cycloheximide, an inhibitor of cytoplasmic protein synthesis, when fed to detached leaves of P. juliflora through transpiration stream in the dark or in light completely prevents in vivo light activation of Vlim and Vmax activities of SPS. In case of spinach, however, cycloheximide feeding affects only Vlim activity while Vmax activity remained unchanged. In contrast, chloramphenicol, an inhibitor of protein synthesis in chloroplast has no effect on the light activation of SPS in Prosopis. The treatment with cycloheximide showed slight reduction in the rate of O2 evolution indicating that cycloheximide had very little effect on overall photosynthesis. These results indicate that short term protein turnover of the SPS protein and some other essential component(s) (e.g., a putative protein that modifies SPS activity) is one of the primary steps in a complex and unique regulatory cascade effecting the reversible light activation of SPS.