English Core Technology

World’s only silkworm bio resource library at Kyushu University Agricultural Research Institute

The silkworm-baculovirus expression system is known as the most efficient protein production system in eukaryotic cells. Silkworm is the most domesticated of all animals, and when viewed as a host of bioactive substances production systems, it has some notable advantages.

(i) It is the only insect species that can be mass-reared, and one will be a small insect plant. This enables scale-up to mass production without complex conditions and eliminates the need for advanced bioreactor design.

(ii)Production of a recombinant protein using an insect has a high expression level in addition to obtaining a modified protein close to that of a mammal.

(iii)Production systems using individual insects are less contaminated with microorganisms and easier to control production conditions than insect cells.

As for the silkworm, the only mutant resource in the world is at Kyushu University, and as a host in functional protein production, we have performed phylogenetic maintenance and systematic selective breeding ahead of the world. Many lines have been managed for more than half a century of breeding records (pedigree: pedigrees) and established as a suburb so that host quality (homogeneity, stability) is ensured. Kyushu University has established its own know-how in grid management and maintenance, and stable supply is guaranteed in the future.

Although there are methods for producing proteins from silkworm-derived expression systems using silkworms, expression systems are basically different from our silkworm-baculovirus expression systems, and both have advantages and disadvantages. . In one example, secretory proteins and membrane proteins often cause secretory defects in the silk gland specialized for embryonic lethality and silk protein secretion of transgenic silkworm due to their toxicity (strong physiological activity) and special structure Although expression is difficult in recombinant silkworms, it can be produced in silkworm-baculovirus expression systems.

The silkworm-baculovirus expression system is capable of expressing all kinds of proteins such as secretory proteins, membrane proteins, cytoplasm, organelle localized proteins, and the silkworm bioresources of Kyushu University already roughly correspond to the types of these proteins. Have found a suitable lineage.

We have established a system for screening and breeding suitable lines for production as needed. Therefore, even if the expression level is low in general silkworm strains, selection of optimal strains according to the target protein and qualitative and quantitative modification of the expressed protein can be comprehensively carried out using the phylogenetic library of Kyushu University I am building a system.

World-leading protein design and processing technology at Kyushu University Research Institute of Engineering

Kyushu University Institute of Engineering has accumulated expertise in site-specific and covalent modification techniques for recombinant proteins, and holds the track record of applying enzyme modification (transglutaminase crosslinking) to the protein engineering field ahead of the world.

For example, in vitro preparation technology of a fusion protein consisting of an antibody fragment scFv and an enzyme (Biotechnol. Bioeng., 2004), anchoring on a cell membrane by introducing a lipid into a recombinant protein (Chem. Eur. J., 2011), We have established efficient conjugation techniques for DNA (Chem. Commun., 2007; Chem. Eur. J., 2011) and RNA (Anal. Chem., 2012) and enzymes.

For example, in vitro preparation technology of a fusion protein consisting of an antibody fragment scFv and an enzyme (Biotechnol. Bioeng., 2004), anchoring on a cell membrane by introducing a lipid into a recombinant protein (Chem. Eur. J., 2011), We have established efficient conjugation techniques for DNA (Chem. Commun., 2007; Chem. Eur. J., 2011) and RNA (Anal. Chem., 2012) and enzymes.

In previous research at the Institute of Engineering Research, alkaline phosphatase that can be expressed in E. coli has been used as a signal amplification unit, but by using a nine-sized silkworm production system, a highly active enzyme (peroxidase) that is difficult to express in microbial hosts Has been successfully expressed as a fusion protein with an antibody binding molecule (Japanese Patent Application No. 2015-032142)

This technology doubles as a proof of concept test for diagnostic drug development, and it is possible to create proteinaceous diagnostic drugs for various antigens using silkworm and baculovirus expression.


Reference Papers