Effect of PrA encoding gene-PEP4 deletion in industrial S. cerevisiae WZ65 on key enzymes in relation to the glycolytic pathway.

摘要

S. cerevisiae proteinase A (PrA) is a member of the aspartic proteinase superfamily. The roles of PrA in S. cerevisiae physiology and cell metabolism are controversial. The objective of the current study was to elucidate the effects of the absence of PrA on key enzymes with regard to the glycolytic flux in industrial S. cerevisiae. The observed activities of hexokinase (HK), phosphofructokinase (Pfk) and pyruvate kinase (PYKi) in PrA-modified S. cerevisiae strains (SC2 and SC3) were lower than that of the wild-type strain (p < 0.01). Compared to other strains, SC3 revealed the lowest activity of three key glycolytic enzymes. Current results imply that PrA in industrial S. cerevisiae may control the glycolytic enzymes expression (HK, Pfk and PYKi) in the direct or indirect manner and thus lead to the delay of cell metabolism. The observed intracellular ATP levels between the wild-type strain and PrA-modified strains (SC1 and SC2) were significantly different (p < 0.01). The pronounced differences of key glycolytic enzymes between the wild-type and PEP4-modified strains were as well characterized by SDS-PAGE. The intracellular protein concentration in the presence of PrA is higher than those of the PrA-modified strains. As a result, the interaction mode of PrA and the glycolytic enzymes was postulated in this work. The findings herein suggest that the glycolytic flux direction and rate may be regulated by vacuolar PrA in industrial S. cerevisiae. The present data obtained provide insights into understanding the roles of PrA in industrial S. cerevisiae