Bacteria Displaying Interleukin-4 Mutants Stimulate Mammalian Cells and Reflect the Biological Activities of Variant Soluble Cytokines

Utilization of Macroalgae for the Production of Bioactive Compounds and Bioprocesses Using Microbial Biotechnology

To achieve sustainable development, alternative resources should replace conventional resources such as fossil fuels. In marine ecosystems, many macroalgae grow faster than terrestrial plants. Macroalgae are roughly classified as green, red, or brown algae based on their photosynthetic pigments. Brown algae are considered to be a source of physiologically active substances such as polyphenols. Furthermore, some macroalgae can capture approximately 10 times more carbon dioxide from the atmosphere than terrestrial plants. Therefore, they have immense potential for use in the environment. Recently, macroalgae have emerged as a biomass feedstock for bioethanol production owing to their low lignin content and applicability to biorefinery processes. Herein, we provided an overview of the bioconversion of macroalgae into bioactive substances and biofuels using microbial biotechnology, including engineered yeast designed using molecular display technology.

Functional characterisation of two receptor interaction determinants in human thymic stromal lymphopoietin

Thymic stromal lymphopoietin (TSLP) is a pro-inflammatory cytokine with important pathological roles in Asthma bronchiale, malignant tumours and other diseases. The heterodimeric human TSLP receptor (hTSLPR) consists of the TSLP-binding subunit (TSLPRα) and the IL-7Rα-subunit. We studied the properties of hTSLP variants with mutations in their bipartite interaction interface towards IL-7Rα. One mutant (T46D/K101D) showed only mild impairment in receptor affinity but a massive reduction in biological activity. To facilitate the future development of hTSLP mutants with drug properties, we have devised a eukaryontic cytokine display assay with activity read-out and intrinsic genotype-phenotype coupling.

Grafting of thrombopoietin-mimetic peptides into cystine knot miniproteins yields high-affinity thrombopoietin antagonists and agonists

Thrombopoietin is the primary regulator of platelet production. We exploited two naturally occurring miniproteins of the inhibitor cystine knot family as stable and rigid scaffolds for the incorporation of peptide sequences that have been shown to act as high-affinity thrombopoietin antagonists. Several miniproteins that antagonistically block thrombopoietin-mediated receptor activation were identified using a microscale reporter assay. Covalent miniprotein dimerization yielded potent bivalent c-Mpl receptor agonists with EC(50) values in the low nanomolar or picomolar range. One selected miniprotein-derived thrombopoietin agonist was almost as active as natural thrombopoietin with regard to stimulation of megakaryocyte colony formation from human bone marrow mononuclear cells, and elicited doubling of platelet counts in mice. Our data suggest that dimeric cystine knot miniproteins have considerable potential for the future development of small and stable receptor agonists. This approach may provide a promising strategy for pharmaceutical interference with other receptors activated by ligand-induced dimerization.

Autodisplay of the protease inhibitor aprotinin in Escherichia coli

The Kunitz type protease inhibitor aprotinin, containing three intramolecular disulfide bonds, was expressed on the surface of Escherichia coli by Autodisplay. For this purpose, the aprotinin gene was fused in-frame to the transporter domain encoding DNA region of the AIDA-I autotransporter protein. Culture of cells supplied with the artificial gene at reducing conditions resulted in the translocation of aprotinin to the cell surface. Correct folding of aprotinin was shown by high affinity to its target enzyme HLE. No surface translocation was detectable under non-reducing conditions, indicating the degradation of aprotinin in the periplasm. By the use of periplasmic-protease defective E. coli strains PW147, PW151, and PW152, under non-reducing conditions, significant amounts of aprotinin appeared in the periplasm but not at the surface. Our results indicate that aprotinin molecules, reaching stable conformation before transport across the outer membrane, are degraded in the periplasm due to proteolysis. In case folding can be prevented, i.e., by blocking disulfide bond formation in the periplasm, aprotinin is translocated and can adopt its active conformation at the cell surface.