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Biomolecular Engineering

  • account_circleYasuaki KawarasakiPhD, Assoc. Prof.
Directed evolution and bioprocesses with industrial importance
Learn from nature, go beyond nature
To contribute to human health and sustainable society, the Biomolecular Engineering Lab is devoted to research and education on novel bioprocesses as well as yeast-based high-throughput analysis systems for genes whose biological functions are not fully understood.
1. Directed evolution of proteins for industrial/diagnostic applications

Directed evolution is a methodology used in protein engineering, in which proteins or microbes are randomly diversified and subjected to functional screening to "breed" mutant strains with desirable properties. Novel methods for efficient mutagenesis and screening have also been developed in our lab.

2. Disease (or aging)-related protein-protein interactions

Interactions between proteins play crucial roles in every biological process including disease development and aging. Our original quantitative screening platform, qY2H, allows us to search a huge cDNA library for proteins that specifically bind to the target (bait)

protein. The reporter gene used in the qY2H is fungal extracellular galactosidase, which is also engineered in the above research project.

3. Fungal gene expression control that is corresponding to nutritional changes in fermentation

We are analyzing industrially useful fungi including yeast Saccharomyces cerevisiae and Aspergillus oryzae. Yeast is inevitable organism in brewing and alcohol production, whereas A. oryzae is the domestic mold which has been traditionally used in Japanese sake- as well as miso- and soysauce-fermentation. Gene expression in those organisms change drastically in the course of fermentation and affect the quality of the fermentation products. The genes and their promoters found in this research project provide a novel bioengineering toolbox and some has been engineered in our research project 1 (see above).

Figure 1
Based on recombinant DNA technologies, molecular biology, and protein expression systems, novel applications as well as analytical methods have been established in our laboratory. Our research focuses on (i) disease (or aging)-related protein-protein interactions, (ii) fungal gene expression control that is corresponding to nutritional changes in fermentation, and (iii) the directed evolution of industrially useful enzymes including laccases. See our web pages at for detailed information.
Figure 2
A schematic drawing of our original high-throughput quantitative yeast 2-hybrid system (qY2H) has been shown. This qY2H features the unique reporter gene, fungal extracellular galactosidase, which allows us to find binding-positive yeast clones on agar plates. The blue halo around the colony is formed by the expressed galactosidase, depending on the intensity of the intracellular protein-protein interaction between protein X and Y*. With this screening platform, we are searching a huge cDNA library for aging- or disease-related protein bindings.
  1. J. Biosci. Bioeng., 113, 154-159 (2012)
  2. J. Biotechnol., 146,151–159, (2010)
  3. Biotech. Progr., 26, 945–53 (2010)
  4. Proc. Natl. Acad. Sci. USA, 102, 10082–10087 (2005)
  5. Nucl. Acid. Res., 31, e126 (2003)
  6. Nucl. Acid. Res., 31, 6953–6962 (2003)