Construction of high sensitive detection system for endocrine disruptors with yeast n-alkane-assimilating Yarrowia lipolytica.

Seoul Center, Korea Basic Science Institute, Seoul 136-713, Korea.
Journal of Microbiology and Biotechnology (Impact Factor: 1.32). 11/2010; 20(11):1563-70.
Source: PubMed

ABSTRACT To construct a highly sensitive detection system for endocrine disruptors, we have compared the activity of promoters with the ALK1, ICL1, RPS7 and TEF1 for heterologous gene in Yarrowia lipolytica. The promoters were introduced into the upstream of lacZ or hERalpha reporter gene, respectively, and the activity was evaluated by beta-galactosidase assay by lacZ or western blot analysis by hERalpha. The expression analysis revealed that the ALK1 and ICL1 promoter were induced by n-decane and by EtOH, respectively. The constitutive promoter of RPS7 and TEF1 showed mostly high level of expression in the presence of glucose and glycerol, respectively. Particularly, the TEF1 promoter showed the highest beta-galactosidase activity and a significant signal by western blotting with the anti-estrogen receptor compared with the other promoters. Moreover, the detection system was constructed with promoters were linked to the upstream of expression vector for hERalpha gene transformed into the Y. lipolytica with a chromosome-integrated lacZ reporter gene under the control of estrogen response elements (EREs). It was indicated that a combination of pTEF1p-hERalpha and CXAU1-2XERE was the most effective system for the E2-dependent induction of the beta-galactosidase activity. This system showed the highest beta-galactosidase activity at 10-6 M E2 and the activity could be detected at even the concentration of 10-10 M E2. As the result, we constructed a strongly sensitive detection system with Y. lipolitica to evaluate recognized/suspected ED chemicals, such as natural/synthetic hormones, pesticides, and commercial chemicals. The results demonstrate the utility, sensitivity and reproducibility of the system for characterizing environmental estrogens.

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    ABSTRACT: Abstract Yarrowia lipolytica has been developed as a production host for a large variety of biotechnological applications. Efficacy and safety studies have demonstrated the safe use of Yarrowia-derived products containing significant proportions of Yarrowia biomass (as for DuPont's eicosapentaenoic acid-rich oil) or with the yeast itself as the final product (as for British Petroleum's single-cell protein product). The natural occurrence of the species in food, particularly cheese, other dairy products and meat, is a further argument supporting its safety. The species causes rare opportunistic infections in severely immunocompromised or otherwise seriously ill people with other underlying diseases or conditions. The infections can be treated effectively by the use of regular antifungal drugs, and in some cases even disappeared spontaneously. Based on our assessment, we conclude that Y. lipolytica is a "safe-to-use" organism.
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    ABSTRACT: In the n-alkane assimilating yeast Yarrowia lipolytica, the expression of ALK1, encoding a cytochrome P450 that catalyzes terminal mono-oxygenation of n-alkanes, is induced by n-alkanes. The transcription of ALK1 is regulated by a heterocomplex that comprises the basic helix-loop-helix transcription activators, Yas1p and Yas2p, and binds to alkane-responsive element 1 (ARE1) in the ALK1 promoter. An Opi1 family transcription repressor, Yas3p, represses transcription by binding to Yas2p. Yas3p localizes in the nucleus when Y. lipolytica is grown on glucose but localizes to the endoplasmic reticulum (ER) upon the addition of n-alkanes. In this study, we showed that recombinant Yas3p binds to the acidic phospholipids, phosphatidic acid (PA) and phosphoinositides (PIPs), in vitro. The ARE1-mediated transcription was enhanced in vivo in mutants defective in an ortholog of the Saccharomyces cerevisiae gene PAH1, encoding PA phosphatase, and in an ortholog of SAC1, encoding PIP phosphatase in the ER. Truncation mutation analyses for Yas3p revealed two regions that bound to PA and PIPs. These results suggest that the interaction with acidic phospholipids is important for the n-alkane-induced association of Yas3p with the ER membrane.
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