title: Assessing functional diversity in the soybean β-substituted alanine synthase enzyme family.
abstract: In plants, proteins of the β-substituted alanine synthase (BSAS) enzyme family perform a diverse range of reactions, including formation of cysteine from O-acetylserine and sulfide, detoxification of cyanide by its addition to cysteine, the breakdown of cysteine into pyruvate, ammonia, and sulfide, and the synthesis of S-sulfocysteine. With the completed genome sequence of soybean (Glycine max (L.) Merr. cv. Williams 82), the functional diversity of the BSAS in this highly duplicated plant species was examined to determine whether soybean BSAS enzymes catalyze the various reactions connected to cysteine metabolism. The 16 soybean BSAS can be grouped into clades that are similar to those observed in Arabidopsis. Biochemical analysis of soybean BSAS proteins demonstrate that enzymes of clades I and III function as O-acetylserine sulfhydrylases for cysteine synthesis, clade II encodes cysteine desulfhydrase activity, and that clade V proteins function as β-cyanoalanine synthase for cyanide detoxification. Although clade IV is similar to Arabidopsis S-sulfocysteine synthase, this activity was not detected in the soybean homolog. Overall, our results show that bioinformatics approach provides a useful method to assess the biochemical properties of BSAS enzymes in plant species.
authors.affiliation: Department of Biology, Washington University in St. Louis, One Brookings Drive, Campus Box 1137, St. Louis, MO 63130, USA.
authors.forename: Hankuil
authors.initials: H
authors.lastname: Yi
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Jez
mesh_terms: D000581:Amidohydrolases / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D055162:Biocatalysis; D019295:Computational Biology; D003545:Cysteine / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D000581:Amidohydrolases; C021590:beta-ureidopropionase; D003545:Cysteine