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Blue and Red Light‐dependent Alterations in the Ratio of two Forms of Glutamine Synthetase in Chlorella kessleri
Author(s) -
Meya Gudrun,
Kowallik W.
Publication year - 1995
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1995.tb00857.x
Subject(s) - cycloheximide , chlorella , glutamine synthetase , phytochrome , biochemistry , darkness , biology , chloroplast , biophysics , biosynthesis , enzyme , glutamine , chemistry , red light , botany , algae , protein biosynthesis , amino acid , gene
Two forms of glutamine synthetase (EC 6.3.1.2) can be separated in crude extracts of Chlorella kessleri on the basis of their different surface charges. The two enzyme forms (GS1 and GS2) respond differently upon transferring the cells from darkness to autotrophic growth in white light: the activity of GS2 increases, that of GS1 remains unchanged. The increase in GS2 activity is only brought about by blue light; in red light GS2 activity appears to be uninfluenced, while that of GS1 increases. There are no indications of wavelength‐dependent oligomerization processes as a cause for the observed activity alterations. There is however, a strong influence of inhibitors of protein biosynthesis. Cycloheximide and lincomycin both affect the blue light‐dependent increase in activity of GS2, cycloheximide preventing that of GS1 in red lgiht completely. Since literature data point to localization of GS2 in the chloroplast, and GS1 in the cytosol, the data are discussed in view of two different photoreceptors involved in the regulation of the amounts of GS1 and GS2 in different compartments of the Chlorella cell.