Modification of thiamine pyrophosphate dependent enzyme activity by oxythiamine inSaccharomyces cerevisiaecells

Abstract

Oxythiamine is an antivitamin derivative of thiamine that after phosphorylation to oxythiamine pyro phosphate can bind to the active centres of thiamine-dependent enzymes. In the present study, the effect of oxythiamine on the viability of Saccharomyces cerevisiae and the activity of thiamine pyrophosphate dependent enzymes in yeast cells has been investigated. We observed a decrease in pyruvate decarboxylase specific activity on both a control and an oxythiamine medium after the first 6 h of culture. The cytosolic enzymes transketolase and pyruvate decarboxylase decreased their specific activity in the presence of oxythiamine but only during the beginning of the cultivation. However, after 12 h of cultivation, oxythiamine-treated cells showed higher specific activity of cytosolic enzymes. More over, it was established by SDS-PAGE that the high specific activity of pyruvate decarboxylase was followed by an increase in the amount of the enzyme protein. In contrast, the mitochondrial enzymes, pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes, were inhibited by oxythiamine during the entire experiment. Our results suggest that the observed strong decrease in growth rate and viability of yeast on medium with oxythiamine may be due to stronger inhibition of mitochondrial pyruvate dehydrogenase than of cytosolic enzymes.

Chemical and genetic validation of thiamine utilization as an antimalarial drug target

“…8). A similar hypothesis has been put forward for the mode of action of oxythiamine against Saccharomyces cerevisiae 21 . The P. falciparum transketolase (another TPP-utilizing enzyme) has recently been shown in in vitro studies to bind to, and be inactivated by, OxPP 32 , providing additional support for our model.…”

“…Studies in yeast showed that oxythiamine reduces the uptake of thiamine by 45% (ref. 20) and inhibits TPP-dependent enzymes 21 . Furthermore, oxythiamine inhibits cancer cell growth by acting as a thiamine antagonist and an inhibitor of transketolase 22 .…”

Proteins of unknown biochemical function - A persistent problem and a roadmap to help overcome it

“…Furthermore, overexpressing an Arabidopsis protein in yeast (Saccharomyces cerevisiae) increased resistance to oxythiamin (Goyer et al, 2013). These data indicate that this Nudix subfamily is involved in removing toxic forms of thiamin diphosphate before it can cause damage by displacing the native cofactor from thiamin diphosphate-dependent enzymes, which both oxythiamin and oxothiamin diphosphate do very effectively (Tylicki et al, 2005). Note that without the cross-kingdom comparative Figure 1.…”

Enzymes of the central carbon metabolism: Are they linkers between transcription, DNA replication, and carcinogenesis?

“…Decreased expression of OGDH caused lower viability of yeast cells [139]. Interestingly, occurrence of heterotetrameric isoform of OGDH, called 2-oxoglutarate dehydrogenase-like protein (OGDHL), localized in mitochondria, was reported [140,141].…”