Discovery of Several Novel Targets that Enhance β-Carotene Production in Saccharomyces cerevisiae

Abstract

β-Carotene is the precursor of vitamin A, and also exhibits multiple pharmaceutical functions by itself. In comparison to chemical synthesis, the production of β-carotene in microbes by metabolic engineering strategy is relatively inexpensive. Identifying genes enhancing β-carotene production in microbes is important for engineering a strain of producing higher yields of β-carotene. Most of previous efforts in identifying the gene targets have focused on the isoprenoid pathway where the β-carotene biosynthesis belongs. However, due to the complex interactions between metabolic fluxes, seemingly irrelevant genes that are outside the isoprenoid pathway might also affect β-carotene biosynthesis. To this end, here we provided an example that several novel gene targets, which are outside the isoprenoid pathway, have improving effects on β-carotene synthesis in yeast cells, when they were over-expressed. Among these targets, the class E protein of the vacuolar protein-sorting pathway (Did2) led to the highest improvement in β-carotene yields, which was 2.1-fold to that of the corresponding control. This improvement was further explained by the observation that the overexpression of the DID2 gene generally boosted the transcriptions of β-carotene pathway genes. The mechanism by which the other targets improve the production of β-carotene is discussed.

Enhanced β-carotene production by promoting the multivesicular body (MVB) pathway in Yarrowia lipolytica

“…cerevisiae [12,18]. For example, the incorporation of the Did2 gene, a member of the MVB sorting pathway, led to the most significant improvement of β-carotene yield by engineered S. cerevisiae [13]. The YL-C1 strain is an engineered Y. lipolytica with basal β-carotene producing capacity.…”

“…Overexpression of the genes Tif 5 (a translation initiation factor), Voa1 (vacuolar H(C)-ATPase subunit 1), and Did2 (a subunit in the MVB sorting pathway) genes enhanced the production of β-carotene in S. cerevisiae [13]. Overexpression of the Did2 gene led to a 2.1-fold improvement of β-carotene production in S. cerevisiae [13]. In this study, we integrated the Did2 gene into the engineered Y.…”

“…The genes Cab1, Nsg1, Erg13, and Erg27 could promote β-carotene biosynthesis in S. cerevisiae as these genes involved in lipid biosynthesis [12]. The VOA1 improves the production of β-carotene in S. cerevisiae because VOA1 may result in a low pH of cell membranes [13].…”

Mechanisms of VPS29 gene in carotenoid deposition in the adductor muscles of QN Orange scallops

“…The VPS gene was first investigated in the cooperative contribution of certain proteins responsible for anthocyanin accumulation in tomatoes [10]. Recently, VPS genes have been reported to function in the increase of carotenoids in Saccharomyces cerevisiae [8]. Furthermore, homologous VPS was found necessary for the formation of deep-orange pigments in Drosophila [11].…”

“…Among the DEGs and differentially expressed proteins (DEPs) between the two types of adductor muscles, the vacuolar protein sorting 29 (VPS29) was the only gene that is richer at both mRNA and protein level in the orange adductor muscles. The VPS gene has been shown to increase the β-carotenoid yields in Saccharomyces cerevisiae [8]. However, the exact role of VPS29 in the accumulation of carotenoids remains unknown in QN Orange scallops.…”