Human modified 47 kDa Pfk-M enzyme might be the pivotal factor of enhanced glycolysis in cancer cells. It is more susceptible to activation by specific effectors and resistant to feed-back inhibition. It can be encoded by artificially prepared sfPFKM gene. Highly active Pfk-M enzymes cause increased cytosolic NADH levels in cancer cells and in S. cerevisiae transformants with the inserted human sfPFKM gene. Imbalanced NADH/NADPH ratio was observed in the yeast sfPFKM transformant that prevented its growth in maltose medium. The purpose of this work was to insert the MAEA gene encoding cytosolic NADP+ dependent malic enzyme in the yeast sfPFKM transformant. The modified bacterial MAEA gene encoded the protein that was expected to improve the pyrimidine nucleotide ratios in the cells and consequently enable growth of sfPFKM/MAEA strain in maltose. After successful insert of MAEA gene into S. cerevisiae/sfPFKM, high NADP+ specific malic enzyme activities were detected. We found that the strains grew in maltose with the best specific growth coefficients detected in 0,05 % maltose media with added amino acids, glutamate and glutamic acid, and malate. We monitored specific growth rate, consumption of maltose and formation of ethanol, glycerol and acetate. To conclude the insertion of MAEA gene enabled growth of S. cerevisiae/sfPFKM/MAEA strain on maltose, most probably by improving NADH/NADPH ratio in the cytosol.
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