Generation of building blocks for synthesis of filter membranesBio VI
The iron transporter FhuA - Ferric hydroxamate uptake protein component A is a channel protein produced by the bacterium Escherichia coli which was tailored for the generation of synthetic membranes using FhuA proteins and polymers. The FhuA protein forms a permeable channel with a uniform pore size from 2.5 to 3.0 nm and a barrel-like structure. Lysine residues were specifically located in a rim on the outer surface of the channel above the transmembrane region for the attachment of polymer chains. This design enabled the grafting of PNIPAAm polymer chains from the outer FhuA channel surface. In the future, the synthesized building blocks of the FhuA channel proteins and polymer chains will be used for generation of hybrid membranes for nanofiltration processes. These generated membranes can be applied in the downstream processing as molecular sieves for the separation of different components which is essential for synthesizing sweeteners, pesticides and pharmaceuticals.
In vitro flow cytometry-based screening platform for cellulase engineeringBio VI
Screening technologies are of pivotal importance for tailoring biocatalysts in directed evolution, as millions of mutant enzyme variants could be generated in every trial. Hence, ultrahigh throughput screening techniques have been developed in order to still complete such trials in a reasonable amount of time. These techniques are well capable of analyzing up to 107 events per hour and thus can analyze the complete coverage of a generated protein sequence with high efficiency.
This technology becomes even more powerful if it is coupled with a cell-free enzyme expression technique. This expression method enables the experimentator to reduce diversity loss when transforming mutant libraries into expression hosts, to design enzymes of animal or human origin or even perform directed evolution of toxic enzymes.
The first ever combination of such a cell-free compartmentalization platform with a flow cytometry-based screening has been achieved in the InVitroFlow technology and successfully applied to directed evolution of cellulose enzymes.
Screening through the PLICable promoter toolbox enhances protein production in Escherichia coliBio VI
Escherichia coli is a common host for recombinant protein production in which product titers are highly dependent on the employed expression system. Thereby, promoters are a key element to control gene expression levels. In this study, a novel PLICable promoter toolbox was developed. It enables the identification of the most suitable promoter out of ten IPTG-inducible promoters (T7, A3, lpp, tac, pac, Sp6, lac, npr, trc and syn) for high level protein production in a single cloning step and after a screening experiment.