The invention generally relates to engineered prephenate dehydrogenases and arogenate dehydrogenases and methods of using the same. More specifically, the invention relates in part to compositions including engineered prephenate dehydrogenases (PDH) polypeptides and engineered arogenate dehydrogenase (ADH) polypeptides with altered substrate preferences and tyrosine sensitivities and methods of using the same.

A recombinant yeast is constructed by introducing an expressed gene of exogenous Fructose-6-phosphate phosphoketolase into a modified yeast cell, and the modified yeast cell is a yeast cell with a metabolic pathway for synthesizing tyrosol via Erythrose-4-phosphate and phosphoenolpyruvate. The present invention discloses for the first time that in the process of expressing Fructose-6-phosphate phosphoketolase in a yeast, Fructose-6-phosphate is synthesized into beta-D-Fructose 1,6-bisphosphate and also catalyzed into Erythrose-4-phosphate and Acetyl-phosphate, and Xylulose-5-phosphate is catalyzed into Glyceraldehydes-3-phosphate and Acetyl-phosphate, which change the metabolic flux distribution of carbon in the yeast, enhance the synthesis of Erythrose-4-phosphate as an important intermediate for the biosynthesis of tyrosol, optimize the metabolic pathway for synthesizing tyrosol, and increase the yields of tyrosol and its derivatives such as hydroxytyrosol.

The invention generally relates to engineered prephenate dehydrogenases and arogenate dehydrogenases and methods of using the same. More specifically, the invention relates in part to compositions including engineered prephenate dehydrogenases (PDH) polypeptides and engineered arogenate dehydrogenase (ADH) polypeptides with altered substrate preferences and tyrosine sensitivities and methods of using the same.

The present disclosure describes the engineering of microbial cells for fermentative production of tyramine and provides novel engineered microbial cells and cultures, as well as related tyramine production methods.

The present disclosure relates to the use of host cell protein biomarkers to assess disulfide bond reduction in compositions comprising a protein of interest. In some embodiments, the disclosure relates to methods of predicting the occurrence of disulfide bond reduction or low molecular weight protein species in compositions comprising a protein of interest, wherein the expression or activity level of at least one host cell protein is measured and provides a benchmark value associated with the occurrence of disulfide bond reduction or low molecular weight species of said protein of interest. In some embodiments, the disclosure relates to methods of producing a protein of interest, wherein host cells capable of producing the protein of interest are cultured, the expression or activity level of at least one host cell protein is measured, and downstream isolation of the protein of interest is informed by the host cell protein measurements.

The present disclosure describes the engineering of microbial cells for fermentative production of tyramine and provides novel engineered microbial cells and cultures, as well as related tyramine production methods.

The invention relates to a method for production of tyrosol, wherein a transgenic bacterial cell that heterologously expresses phenylpyruvate decarboxylase and that overexpresses phospho-2-dehydro-3-deoxyheptonate and prephenate dehydrogenase, and wherein pheAL and feaB are both inactivated or removed, is grown in a medium comprising a metabolic precursor of phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P), particularly glucose, and optionally, phenylalanine as a supplement; and tyrosol is extracted from said medium. The invention also relates to a method for production of salidroside, wherein the transgenic cell additionally heterologously expresses uridine diphosphate dependent glycosyltransferase (UGT85A1, EC:2.4.1.)

The invention concerns novel enzymes having an arogenate dehydrogenase activity, in particular arogenate dehydrogenase enzymes of plants, and the genes encoding said enzymes. The inventive arogenate dehydrogenase enzymes catalyze the last stage of the metabolic pathway of tyrosine biosynthesis, and constitute, as such, potential targets of herbicides. Hence the invention also concerns a method for identifying herbicide compounds targeting said enzymes, said herbicide compounds preventing tyrosine biosynthesis by being fixed on said enzymes. The invention further concerns transgenic plants tolerant to herbicide compounds targeting an enzyme involved in the tyrosine biosynthesis pathway, in particular an enzyme involved in the transformation of L-tyrosine prephenate, in particular an arogenate dehydrogenase enzyme. Said plants become tolerant by expression in their tissues of a prephenate dehydrogenase enzyme, said enzyme being insensitive to said herbicide compounds and enabling the plant to synthetize tyrosine despite being treated with said herbicide compounds.

Disclosed herein are transgenic cells expressing a heterologous nucleic acid encoding a prephenate dehydrogenase (PDH) protein, a heterologous nucleic acid encoding a homogentisate solanesyl transferase (HST) protein, a heterologous nucleic acid encoding a deoxyxylulose phosphate synthase (DXS) protein, or a combination of two or more thereof. In particular examples, the disclosed transgenic cells have increased plastoquinone levels. Also disclosed are methods of increasing cell growth rates or production of biomass by cultivating transgenic cells expressing a heterologous nucleic acid encoding a PDH protein, a heterologous nucleic acid encoding an HST protein, a heterologous nucleic acid encoding a DXS protein, or a combination of two or more thereof under conditions sufficient to produce cell growth or biomass.

The present invention provides engineered phenylalanine ammonia-lyase (PAL) enzymes comprising one or more mutations that increase the enzymes' tyrosine ammonia-lyase (TAL) activity. Also provided are plants comprising the engineered PAL enzymes and methods of using these plants to sequester CO.sub.2 or produce phenylpropanoid-derived products.