title: Identification of amino acid residues essential for onion lachrymatory factor synthase activity.
abstract: Lachrymatory factor synthase (LFS), an enzyme essential for the synthesis of the onion lachrymatory factor (propanethial S-oxide), was identified in 2002. This was the first reported enzyme involved in the production of thioaldehyde S-oxides via an intra-molecular H(+) substitution reaction, and we therefore attempted to identify the catalytic amino acid residues of LFS as the first step in elucidating the unique catalytic reaction mechanism of this enzyme. A comparison of the LFS cDNA sequences among lachrymatory Allium plants, a deletion analysis and site-directed mutagenesis enabled us to identify two amino acids (Arg71 and Glu88) that were indispensable to the LFS activity. Homology modeling was performed for LFS/23-169 on the basis of the template structure of a pyrabactin resistance 1-like protein (PYL) which had been selected from a BLASTP search on SWISS-MODEL against LFS/23-169. We identified in the modeled structure of LFS a pocket corresponding to the ligand-binding site in PYL, and Arg71 and Glu88 were located in this pocket.
authors.affiliation: Somatech Center, House Foods Corporation, Yotsukaido, Chiba, Japan. n-masamura@housefoods.co.jp
authors.forename: Noriya
authors.initials: N
authors.lastname: Masamura
authors.forename: Wakana
authors.initials: W
authors.lastname: Ohashi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Tsuge
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Imai
authors.forename: Anri
authors.initials: A
authors.lastname: Ishii-Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirota
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nagata
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Kumagai
mesh_terms: D000490:Allium / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D055162:Biocatalysis; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019746:Intramolecular Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D019746:Intramolecular Oxidoreductases