Home ＞GCOE Researchers ＞Youji SAKAGAMI

GCOE Researchers

Youji SAKAGAMI

Affiliation
/Position		 Graduate School of Bioagricultural Sciences, Department of Applied Molecular Biosciences, Professor
Doctorate Doctor of Agriculture
Research interests Chemical biology, Biologically active peptides
address ysaka＠agr.nagoya-u.ac.jp
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+81-52-789-4116
  Laboratory

Outline of research

I have been studying biologically active endogenous substances, including pheromones and hormones in both microbes and plants. Specifically, I have focused our studies on biologically active peptides with distinctive characteristics; in most cases, these molecules undergo specific posttranslational modifications, as described below:

  1. Conjugation tube inducers in basidiomycetous yeast: Heterotypic yeast-like cells in the sexual stage of basidiomycetes mate by extending conjugation tubes toward each other. We identified three peptide pheromones that induce the formation of conjugation tubes, and determined their chemical structures. These peptides have a peculiar chemical structure in which the C-terminal cysteine is modified by a farnesyl group. This discovery led to a pioneering study of what we now call "isoprenoidal proteins" (Science, 1981; Biochemistry, 1984; and others).
  2. Enterobacteria: Streptococcus (Enterococcus) faecalis agglutinates to promote the transfer of plasmids between cells of the same species. We isolated and analyzed the amino acid sequences of several peptides expressed by several different plasmids; these peptides act as sex pheromones which induce this agglutination (Science, 1983, J.Biol.Chem.,1988; and others).
  3. We isolated a peptide consisting of five amino acid residues as a growth factor for cultured plant cell, determined its structure, and named it phytosulfokine (PSK). PSK included two sulfated tyrosine residues, and was the first reported example of a sulfated tyrosine occurring in plants. We next cloned the precursor and receptor genes for PSK and demonstrated physiological functions of PSK in individual plants (PNAS, 1996, 1997, 1999; Science, 2002 and others).
  4. Bacillus subtilis acquires competence under conditions of high cell density. We theoretically predicted the chemical structure of quorum-sensing pheromone, ComX, which induces this competence, and then confirmed the structure by chemical synthesis. A tryptophan residue in this peptide was modified with geranyl (C-10) or farnesyl (C-15) group. In addition, we revealed another peculiar structural feature: another five-membered ring is formed on a tryptophan residue in this molecule, which represents a novel type of posttranslational modification in an isoprenoid (Nature Chemical Biology, 2005 and others).
  5. The CLV genes control differentiation of shoot apex in Arabidopsis. CLV1 and CLV2 encode receptor-like proteins, and CLV3 encodes peptide ligand. Using MALDI TOF-MS, we revealed the structure of the peptide ligand by analyzing a slice of callus overexpressing the CLV3 gene. This peptide (MCLV3) is composed of 12 amino acid residues, and its unusual characteristics include the hydroxylation of two proline residues (Science, 2006).

References

  1. Yajima, A. et al. (2008) Synthesis and absolute configuration of hormone α1. Nat. Chem. Biol., 4: 235-237
  2. Ogawa M. et al. (2008) Arabidopsis CLV3 peptide directly binds CLV1 ectodomain. Science, 319: 294
  3. Mori, D. et al. (2007) Spongolactams, farnesyl transferase inhibitors from a marine sponge: Isolation through an LC/MS-guided assay, structures, and semisynthesis. Org. Chem., 72: 7190-7198
  4. Shinohara H. et al. (2007) Identification of ligand binding site of phytosulfokine receptor by on-column photoaffinity labeling. J. Biol. Chem., 282: 124-131.
  5. Kondo T. et al. (2006) A plant peptide encoded by CLV3 identified by in situ MALDI-TOF MS analysis. Science, 313: 845-848.
  6. Okada M. et al. (2006) Chemical synthesis of ComX pheromone and related peptides containin isoprenoidal tryptophan residues. Tetrahedron, 62: 8907-8918.
  7. Matsubayashi, Y., & Sakagami, Y. (2006) Peptide Hormones in Plants.Ann. Rev. Plant Biol., 57: 649-674
  8. Qi J. et al. (2005) Characterization of a Phytophthora mating hormone. Science, 309: 1828.
  9. Okada M. et al. (2005) Structure of the Bacillus subtilis quorum-sensing peptide pheromone ComX. Nat. Chem. Biol., 1: 23-24.
  10. Ojika M. et al. (2004) Synthesis of cystothiazole A and its stereoisomers: importance of stereochemistry for antifungal activity. Tetrahedron 60: 187-194.

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