Inhibition of pteridine biosynthesis eliminates blue-light dependent stimulation of red-light saturated photosynthesis in Laminaria saccharina (L.) Lamouroux.
Blue-light stimulation of red light-saturated photosynthetic oxygen evolution in Laminaria saccharina (L.) Lamouroux could be abolished within 5 days by incubation in a solution of 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I (E.C.3.5.4.16) activity. Photosynthesis in red light was not detectably affected. GTP-cyclohydrolase I, which catalyses the first step in the biosynthetic pathway of pteridines, was shown to be active in Laminaria. Under conditions that lead to complete inhibition of the photosynthetic stimulation, DAHP reduced the content of the pteridines in the tissue considerably. The amount of pterin was about 14%, that of biopterin was about 45% and that of an unidentified pteridine was about 27% of those of the controls. By contrast, the total concentration of flavins (FAD + FMN - riboflavin) was not significantly affected. The results suggest that pterins may be involved in the response of photosynthesis to blue light, possibly participating in photoreception.
Maier
J
J
Institut für Chemische Pflanzenphysiologie, Universität Tübingen, Germany.
Schmid
R
R
D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006136:GTP Cyclohydrolase / Q000037:antagonists & inhibitors; D007042:Hypoxanthines / Q000494:pharmacology; D007795:Laminaria / Q000378:metabolism*; D008027:Light; D010788:Photosynthesis; D011621:Pteridines / Q000378:metabolism*
D004791:Enzyme Inhibitors; D007042:Hypoxanthines; D011621:Pteridines; D006136:GTP Cyclohydrolase; C017202:2,4-diaminohypoxanthine