scholarly journals Opportunities and challenges for the sustainable production of structurally complex diterpenoids in recombinant microbial systems

2017 ◽  
Vol 13 ◽  
pp. 845-854 ◽  
Author(s):  
Katarina Kemper ◽  
Max Hirte ◽  
Markus Reinbold ◽  
Monika Fuchs ◽  
Thomas Brück
Keyword(s):  
Escherichia Coli ◽  
Defense Mechanisms ◽  
Food Additives ◽  
Building Blocks ◽  
Industrial Applications ◽  
Site Directed Mutagenesis ◽  
Terpene Biosynthesis ◽  
Dimethylallyl Diphosphate ◽  
Microbial Systems ◽  
Wall Components

With over 50.000 identified compounds terpenes are the largest and most structurally diverse group of natural products. They are ubiquitous in bacteria, plants, animals and fungi, conducting several biological functions such as cell wall components or defense mechanisms. Industrial applications entail among others pharmaceuticals, food additives, vitamins, fragrances, fuels and fuel additives. Central building blocks of all terpenes are the isoprenoid compounds isopentenyl diphosphate and dimethylallyl diphosphate. Bacteria like Escherichia coli harbor a native metabolic pathway for these isoprenoids that is quite amenable for genetic engineering. Together with recombinant terpene biosynthesis modules, they are very suitable hosts for heterologous production of high value terpenes. Yet, in contrast to the number of extracted and characterized terpenes, little is known about the specific biosynthetic enzymes that are involved especially in the formation of highly functionalized compounds. Novel approaches discussed in this review include metabolic engineering as well as site-directed mutagenesis to expand the natural terpene landscape. Focusing mainly on the validation of successful integration of engineered biosynthetic pathways into optimized terpene producing Escherichia coli, this review shall give an insight in recent progresses regarding manipulation of mostly diterpene synthases.

scholarly journals Human Deoxycytidine Kinase Is a Valuable Biocatalyst for the Synthesis of Nucleotide Analogues

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 997 ◽  
Author(s):  
Katja F. Hellendahl ◽  
Sarah Kamel ◽  
Albane Wetterwald ◽  
Peter Neubauer ◽  
Anke Wagner
Keyword(s):  
Substrate Concentration ◽  
Food Additives ◽  
Product Yield ◽  
Building Blocks ◽  
Product Formation ◽  
Industrial Applications ◽  
Modified Nucleosides ◽  
Deoxycytidine Kinase ◽  
Wide Range ◽  
Substrate Concentrations

Natural ribonucleoside-5’-monophosphates are building blocks for nucleic acids which are used for a number of purposes, including food additives. Their analogues, additionally, are used in pharmaceutical applications. Fludarabine-5´-monophosphate, for example, is effective in treating hematological malignancies. To date, ribonucleoside-5’-monophosphates are mainly produced by chemical synthesis, but the inherent drawbacks of this approach have led to the development of enzymatic synthesis routes. In this study, we evaluated the potential of human deoxycytidine kinase (HsdCK) as suitable biocatalyst for the synthesis of natural and modified ribonucleoside-5’-monophosphates from their corresponding nucleosides. Human dCK was heterologously expressed in E. coli and immobilized onto Nickel-nitrilotriacetic acid (Ni-NTA) superflow. A screening of the substrate spectrum of soluble and immobilized biocatalyst revealed that HsdCK accepts a wide range of natural and modified nucleosides, except for thymidine and uridine derivatives. Upon optimization of the reaction conditions, HsdCK was used for the synthesis of fludarabine-5´-monophosphate using increasing substrate concentrations. While the soluble biocatalyst revealed highest product formation with the lowest substrate concentration of 0.3 mM, the product yield increased with increasing substrate concentrations in the presence of the immobilized HsdCK. Hence, the application of immobilized HsdCK is advantageous upon using high substrate concentration which is relevant in industrial applications.

scholarly journals Overexpression, site-directed mutagenesis, and mechanism of Escherichia coli acid phosphatase

1992 ◽  
Vol 267 (32) ◽  
pp. 22830-22836 ◽  
Author(s):  
K Ostanin ◽  
E.H. Harms ◽  
P.E. Stevis ◽  
R Kuciel ◽  
M.M. Zhou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acid Phosphatase ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis

scholarly journals A genetically detoxified derivative of heat-labile Escherichia coli enterotoxin induces neutralizing antibodies against the A subunit.

1994 ◽  
Vol 180 (6) ◽  
pp. 2147-2153 ◽  
Author(s):  
M Pizza ◽  
M R Fontana ◽  
M M Giuliani ◽  
M Domenighini ◽  
C Magagnoli ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cholera Toxin ◽  
Neutralizing Antibodies ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
E Coli ◽  
Heat Labile ◽  
A Subunit ◽  
Adp Ribosyltransferase ◽  
Derivatives Of

Escherichia coli enterotoxin (LT) and the homologous cholera toxin (CT) are A-B toxins that cause travelers' diarrhea and cholera, respectively. So far, experimental live and killed vaccines against these diseases have been developed using only the nontoxic B portion of these toxins. The enzymatically active A subunit has not been used because it is responsible for the toxicity and it is reported to induce a negligible titer of toxin neutralizing antibodies. We used site-directed mutagenesis to inactivate the ADP-ribosyltransferase activity of the A subunit and obtained nontoxic derivatives of LT that elicited a good titer of neutralizing antibodies recognizing the A subunit. These LT mutants and equivalent mutants of CT may be used to improve live and killed vaccines against cholera and enterotoxinogenic E. coli.

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