Autofluorescence of yeast Saccharomyces cerevisiae cells caused by glucose metabolism products and its methodological implications

Disorders in NADPH generation via pentose phosphate pathway influence the reproductive potential of the Saccharomyces cerevisiae yeast due to changes in redox status

“…Biosynthesis of pyridoxine and riboflavin is based on glucose-derived intermediates formed in the PP pathway. 26 The results demonstrated that the Δzwf1 mutant contained a higher level of pyridoxine in comparison with the WT strain ( Figure 6B). In turn, lower level of this compound was observed in the Δgnd1 and Δgnd2 F I G U R E 3 Activity of glucose-6-phosphate dehydrogenase (Zwf1p), 6-phosphogluconate dehydrogenase (Gnd1p and Gnd2p) and total dehydrogenase activity (sum of both Zwf1p and Gnd1p/ Gnd2p) in the wild-type strain (WT) and Δzwf1, Δgnd1, Δgnd2 mutants.…”

“…29 Biosynthesis of tryptophan in the cells is based on glucosederived intermediates formed in glycolysis and nonoxidative phase of the PP pathway, and is directly dependent on glucose metabolism. 26,46 The increased content of tryptophan observed in the Δzwf1 mutant in comparison to the WT strain ( Figure 6A) may be associated with a higher amount of glucose-6-phosphate in the cells which is not converted to 6-phosphogluconolactone due to the lack of Zwf1p. The surplus of glucose-6-phosphate caused by the blockage of PP pathway can be redirected to different processes including biosynthesis of tryptophan as a result of carbon flow towards glycolysis.…”

Reproductive Potential of Yeast Cells Depends on Overall Action of Interconnected Changes in Central Carbon Metabolism, Cellular Biosynthetic Capacity, and Proteostasis

“…Hence, higher activity of PP pathway enzymes in the case of the Δ hxk2 strain ( Figure 6 C) seems to provide ribose-5-phosphate for exceptionally high ATP synthesis observed in this strain ( Figure 2 A–D). To verify that possibility, determination of riboflavin and tryptophan content was performed as the biosynthesis of riboflavin and tryptophan based on ribose-5-phosphate and other PP pathway intermediates [ 40 ]. There was a significantly higher level of riboflavin in cells of the Δ hxk2 strain in comparison to the WT strain under all conditions utilizing different glucose concentrations ( Figure 6 D).…”

“…Nevertheless, it must be emphasized that the PP pathway and the related glycolysis are regulated depending on cellular demands. Moreover, the PP pathway is not only responsible for production of macromolecular components, such as aromatic amino acids, NADPH, or nucleotides involved in DNA replication, but it also provides ribose-5-phosphate for the de novo synthesis of glucose-derived intermediates, including IMP, ATP, GTP, riboflavin, or tryptophan [ 40 ]. Thus, higher activity of PP pathway enzymes in the case of Δ hxk2 strain ( Figure 6 C) would provide ribose-5-phosphate for exceptionally high ATP level observed in this strain.…”

“…Tryptophan and riboflavin contents were estimated in the cell extracts using TECAN Infinite 200 microplate reader (Tecan Group Ltd., Männedorf, Switzerland) at the characteristic wave-lengths of λ ex = 290 nm and λ em = 325 nm; λ ex =460 nm and λ em = 535 nm, respectively, according to Reference [ 40 ]. The values were expressed in arbitrary units.…”