Lei Wang
 Assistant Professor, The Salk Institute

e-mail: lwang@salk.edu
Lab Homepage: Wang Lab

     Cells use a limited number of molecular building blocks to achieve an amazing variety of functions for life needs. Understanding, utilizing, and enhancing such capabilities depend on how at will we are able to manipulate molecules inside cells. Our laboratory is interested in developing new strategies for molecular evolution and molecular imaging. These new methods will be applied to study cellular functions and to generate new biological activities. We combine chemistry, biochemistry, molecular biology and fluorescence techniques to achieve these goals.

     The biosynthetic machinery of cells can be enhanced. For instance, the genetic code can be expanded to include unnatural amino acids (Figure 1). An orthogonal tRNA/aminoacyl-tRNA synthetase pair can be generated to incorporate a desired unnatural amino acid into proteins in response to a blank codon. A variety of nonproteinogenic amino acids with different chemical and physical properties can now be site-specifically introduced into proteins directly in live cells. In addition to providing new tools for studying proteins and their related processes, the diversity of the building blocks also provides an opportunity for creating novel properties and exploring the evolutionary implications.

Figure 1. By generating an orthogonal tRNA/synthetase pair, unnatural amino acids can be
site-specifically incorporated into proteins directly in cells.

     In the meantime, the ability to sample large sequence spaces of biomolecules is also crucial for appreciating the diversity. For instance, somatic hypermutation, a process B lymphocytes use to optimize immunoglobulins, was harnessed to mutate target genes directly in live cells in order to sample protein sequence space efficiently (Figure 2). Large genetic diversity can be easily generated simply by growing more cells, and the cells were screened efficiently by fluorescence-activated cell sorting. By using this approach red fluorescent proteins were evolved with properties that were unattainable with conventional means. Such in vivo evolution methods would enable us to assess and create challenging properties that necessitate a native cellular environment.

     We are now developing new methods for evolving molecules in different cell types and organisms. These new directed evolution strategies and the increased diversity of the building blocks should enable us to biosynthesize molecules, modules and functions for tailored purposes. Together with chemically synthesized small molecules and nanoentities, they will be applied to study cellular processes and to generate new functions for biomedical applications.

Figure 2. Protein evolution in mammalian cells via somatic hypermutation (SHM) and fluorescence-activated cell sorting (FACS). At the bottom are purified monomeric red fluorescent protein samples evolved using this method (mRaspberry and mPlum) in visible (left) and fluorescence (right).

    Wang, L., Schultz, P. G. (2005). Expanding the Genetic Code. Angew. Chem. Int. Ed., 44: 34-66.

    Wang, L., Jackson, W.C., Steinbach, P.A., Tsien, R.Y. (2004). Evolution of New Nonantibody Proteins via Iterative Somatic Hypermutation. Proc. Natl. Acad. Sci. U.S.A. 101: 16745-16749.

    Wang, L. (2003). Expanding the Genetic Code, Science, 302: 584-585.

    Wang, L., Zhang, Z., Brock, A., Schultz, P. G. (2003). Addition of the Keto Functional Group to the Genetic Code of Escherichia coli, Proc. Natl. Acad. Sci. U.S.A., 100: 56-61.

    Wang, L., Brock, A., Herberich, B., Schultz, P. G. (2001). Expanding the Genetic Code of Escherichia coli. Science, 292: 498-500.

    Wang, L., Schultz, P.G. (2001). A General Approach for the Generation of Orthogonal tRNAs. Chem. Biol., 8: 883-90.

    Wang, L., Magliery, T. J., Liu, D. R., Schultz, P. G. (2000). A New Functional Suppressor tRNA/Aminoacyl-tRNA Synthetase Pair for the in vivo Incorporation of Unnatural Amino Acids into Proteins. J. Am. Chem. Soc., 122: 5010-1.

Lei Wang received his Ph.D. from University of California at Berkeley. He did postdoctoral studies at UCSD, where he was a Merck Fellow of the Damon Runyon Cancer Research Foundation. He was named to the MIT Technology Review TR100 as one of the world’s top young innovators. He was awarded the Amersham Biosciences and Science Grand Prize for Young Scientists by American Association for the Advancement of Science and the Grand Prize of Collegiate Inventors Competition by National Inventors Hall of Fame.