BBa_K3584000 is the coding sequence of a polyphenol oxidase (PPO) from Pleurotus ostreatus, which is different from the present enzymes showing the similar activity. PPO is a group of enzyme that are able to oxidize phenol or polyphenol by molecular oxygen to form the corresponding quinone. In a broad sense, polyphenol oxidase can be divided into three categories: monophenol monooxidase (tyrosinase, EC.22.214.171.124), bisphenol oxidase (catechol oxidase, EC. 126.96.36.199) and laccase (laccase, EC.188.8.131.52). Among these three types of polyphenol oxidase, catechol oxidase is mainly distributed in plants, and the polyphenol oxidase in microorganisms mainly includes laccase and tyrosinase. The polyphenol oxidase mentioned in most of the literature is generally the collective name of catechol oxidase and laccase.
BBa_K3584006 is composite part containing the coding sequences of TyrR gene and green fluorescent protein (GFP) which are controlled by constitutive promoter p14 and tyrP promoter, respectively.
TyrR is transcriptional regulatory protein that is involved in transcriptional regulation of aromatic amino acid biosynthesis and transport. The activity of the TyrR protein is modulated by the binding of one or more of the aromatic amino acids (phenylalanine, tyrosine and tryptophan). These amino acids act as co-effectors which bind to the TyrR protein to form an active regulatory protein. TyrR causes positive effects on the tyrP promoter.
Our team aimed to alleviate the harm from gut-derived toxins in patients of chronic kidney disease by using synthetic live bacteria gut metabolize toxins, which E. coli was engineered to express polyphenol oxidase (PPO) proteins. Moreover, PPO protein degrades p-cresol (precursor of p-cresyl sulfate), making it impossible to synthesize toxin which is harmful to renal and heart function. And the tyrosine operon is used as a biological switch, which is induced by dietary amino acid, to produce toxin-degrading enzyme in appropriate time. As the beginning of the project, the part BBa_K3584006 was constructed as a GFP reporting system to verify the function of the tyrosine induced promoter.
BBa_K3584008 is composite part containing the coding sequences of TyrR gene and polyphenol oxidase (PPO) proteins which are controlled by constitutive promoter p14 and tyrP promoter, respectively.
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