Memories of late professor Hideaki Yamada, a giant in enzyme engineering, and successive activities stemmed from his philosophy

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Basics and applications of gut bacterial lipid-metabolizing enzymes- A tribute to the late Professor Hideaki Yamada

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Multiple reactions for the asymmetric synthesis of unusual amino acids

Unusual amino acids, such as γ-amino butyric acid (GABA) derivatives and hydroxy amino acids, are known to have worthwhile physiological activities on the mammals or are used as chiral building blocks in the chemical synthesis of other compounds. So far, we have been screening microbial enzymes in order to develop novel biocatalysts useful for various kinds of bioproduction process. In the course of the screening, a variety of enzymes were found to catalyze unique reactions acting to amino acids and the related compounds. Therefore, we suitably combined these biocatalysts and chemical reactions to make multiple reaction systems, by which several unusual amino acids were obtained with high steric purity. Optically active dicarboxylic acid monoamides (chiral half amides) such as (R)-3-(4-chlorophenyl)-glutaric acid monoamide [(R)-CGM] are easily converted into corresponding chiral 3-substituted GABA derivatives by a coupling of Hofmann rearrangement. Some chiral 3-substituted GABA derivatives are used as important medicinal drugs. Chiral half amides are available via desymmetric hydrolysis of prochiral cyclic imides. For the reactions, stereoselective imide-hydrolyzing enzymes (imidases) are necessary to obtain chiral half amides effectively. Then we searched microbial imidases for desymmetric hydrolyze of several cyclic imides. As the result of the microbial screening, Burkholderia phytofirmans DSM17436 was found to have the imidase activity hydrolyzing a cyclic imide, 3-(4-chlorophenyl)glutarimide [CGI], into (R)-CGM with 97.5% ee. An imidase of B. phytofirmans was purified through a classical column chromatographic separation method. The identified enzyme, BpIH, has similarity with an allantoinase of Pseudomonas fluorescens and a 5-benzyl-2,4-thiazolidindione-hydrolyzing enzyme of Brevibacterium linens C-1. Consequently, bioconversion of prochiral CGI into (R)-CGM was achieved with a yield of 99% and 99% ee with the recombinant E. coli cells expressing BpIH. Please click Additional Files below to see the full abstract

Hannaella oleicumulans sp. nov. and Hannaella higashiohmiensis sp. nov., two novel oleaginous basidiomycetous yeast species

滋賀県の土壌から新種の油脂酵母2種を発見 --日本の土壌微生物の可能性を開拓--. 京都大学プレスリリース. 2023-10-04.Two-of-a-kind strike oil: Discovery of oil-forming yeast species boosts hope for reducing carbon dioxide emissions. 京都大学プレスリリース. 2023-10-04.Three strains of novel oleaginous yeast species were isolated from soil samples collected in Shiga Prefecture, Japan. The sequences of the internal transcribed spacer (ITS) region and the D1/D2 region of the large subunit (LSU) of the rRNA genes indicated that these novel yeast species are members of the genus Hannaella. The results of molecular phylogenetic analysis indicated that strains 38–3 and 8s1 were closely related to Hannaella oryzae. They differed by 10 nucleotide substitutions and one gap (1.77 %) in the D1/D2 region of the LSU of the rRNA genes and by 17–18 nucleotide substitutions and 10–11 gaps (5.45–5.85 %) in the ITS region. Strain 51–4 differed from the type strain of the most closely related species, Hannaella pagnoccae, by 26 nucleotide substitutions (4.46 %) in the D1/D2 region of the LSU of the rRNA genes and by 20 nucleotide substitutions and six gaps (5.42 %) in the ITS region. The names proposed for these previously undescribed species are Hannaella oleicumulans sp. nov. and Hannaella higashiohmiensis sp. nov