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The high-valent iron-oxo species formed in the non-heme diiron enzymes have high oxidative reactivity and catalyze difficult chemical reactions. Although the hydroxylation of inert methyl groups is an industrially promising reaction, utilizing non-heme diiron enzymes as such a biocatalyst has been difficult. Here we show a three-component monooxygenase system for the selective terminal hydroxylation of α-aminoisobutyric acid (Aib) into α-methyl-D-serine. It consists of the hydroxylase component, AibH1H2, and the electron transfer component. Aib hydroxylation is the initial step of Aib catabolism in Rhodococcus wratislaviensis C31-06, which has been fully elucidated through a proteome analysis. The crystal structure analysis revealed that AibH1H2 forms a heterotetramer of two amidohydrolase superfamily proteins, of which AibHm2 is a non-heme diiron protein and functions as a catalytic subunit. The Aib monooxygenase was demonstrated to be a promising biocatalyst that is suitable for bioprocesses in which the inert C–H bond in methyl groups need to be activated., 地球外有機化合物に対する微生物代謝の解明から全く新規な酵素系を発見 --生命分子進化の理解や産業応用に期待--. 京都大学プレスリリース. 2021-01-20.

Anthocyanin accumulation in grape berry skin is a crucial determinant of red/black grape berry quality. Recently, viticulture has been hampered by the issue of global warming, which has led to loss of anthocyanin accumulation in berry skin. The objectives of this study were to investigate the effect of allantoin on anthocyanin accumulation in berry skins of field-grown grapevines and to elucidate the molecular mechanism of the allantoin-induced anthocyanin accumulation in the berry skins. Allantoin enhanced anthocyanin accumulation in grape cultured cells and berry skins from field-grown grapevines at the early stage of ripening. MybA1 and UFGT, which encode the key transcription factor and enzyme in anthocyanin biosynthesis, were upregulated in allantoin-treated berry skins. Allantoin seems to increase the contents of delphinidin-based anthocyanin 3-glucosides in berry skins through the upregulation of F3'5'H gene that drives the synthesis of delphinidin-based anthocyanin 3-glucosides, compared with control berry skins. Allantoin increased soluble sugar contents in berries 10 days after treatment and upregulated abscisic acid (ABA)-responsible HT6 gene that encodes a key hexose transporter in sugar accumulation during ripening, in berry skins. These results suggested that physiological changes in allantoin-treated grape berries occurred in an ABA-dependent manner. Allantoin produced bioactive ABA through the β-glucosidase-catalyzed hydrolysis of glucose-conjugated ABA but not through the ABA biosynthesis by NCED, a key enzyme in ABA biosynthesis, in berry skins. Allantoin application in viticulture under global warming conditions is expected to contribute to mitigating loss of red/black berry skin color.

The microbial transformation of cyclic imides was investigated. Blastobacter sp. A17p-4 was used as a model strain for metabolism, enzyme, and physiology analysis based on its diversity of cyclic amide metabolism, including cyclic imides and cyclic ureides. Imidase and half-amidase, which are the key enzymes in this transformation, from Blastobacter sp. A17p-4 have been studied together with cyclic ureide transforming enzymes, that is, d -hydantoinase, N-carbamoyl- d -amino acid amidohydrolase, useful for d -amino acid production from dl -5-monosubstituted hydantoin. d -Hydantoinase functions in the metabolism of bulky cyclic imides, while imidase functions in that of simple cyclic imides in combination with half-amidase, which functions in the hydrolysis of the imidase reaction products, half-amides. Imidase and half-amidase are different from reported cyclic amide–metabolizing enzymes, and are widely found in bacteria, yeasts, and molds. The cyclic imide metabolism and the enzymes involved were applied for the production of useful organic acid, such as pyruvate and fine synthesis of optically active α-mercapto acids and half-amides useful as pharmaceutical intermediates.

( R )-Isovaline has potential applications in drug development, and therefore the development of an efficient method for the production of ( R )-isovaline is desired. Herein we have investigated the asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide into ( S )-2-ethyl-2-methyl-malonamic acid, a useful synthetic intermediate in the production of ( R )-isovaline, using Cs AM, which is a recombinant amidase originally derived from Cupriavidus sp. KNK-J915. The produced ( S )-2-ethyl-2-methyl-malonamic acid (98.6% ee) could be easily converted into ( R )-isovaline by the Hofmann rearrangement. Starting from diethyl 2-methylmalonate, we obtained ( R )-isovaline (99.1% ee) in 58.6% yield over eight steps, including the Cs AM-catalyzed asymmetric hydrolysis of 2-ethyl-2-methyl-malonamide.

A novel amidase ( Cs AM) acting on ( R , S )- N -benzyl-3-piperidinecarboxamide was purified from Cupriavidus sp. KNK-J915 (FERM BP-10739) and characterized. The enzyme acts on ( R , S )- N -benzyl-3-piperidinecarboxamide S -selectively to yield ( R )- N -benzyl-3-piperidinecarboxamide. Analytical gel filtration column chromatography and SDS-PAGE revealed that the enzyme is a tetramer with a subunit of approximately 47 kDa. It has a broad substrate spectrum against nitrogen-containing heterocyclic amides. Its optimal pH and temperature are 8.0–9.0 and 50 °C, respectively. The Cs AM gene was cloned and sequenced, and it was found to comprise 1341 bp and encode a polypeptide of 46,388 Da. The deduced amino acid sequence exhibited 78% identity to that of a putative amidase ( Cn AM) from Cupriavidus necator JMP134. The cultured cells of recombinant Escherichia coli producing Cn AM could be used for the S -selective hydrolysis of ( R , S )- N -benzyl-3-piperidinecarboxamide but could not be used for the S -selective hydrolysis of ( R , S )-3-piperidinecarboxamide because of its very low level of selectivity. In contrast, the cultured cells of recombinant E . coli producing Cs AM could hydrolyze both ( R , S )- N -benzyl-3-piperidinecarboxamide and ( R , S )-3-piperidinecarboxamide with high S -selectivity.

Aims Micro-organisms were screened for their ability to produce (R)-3-(4-chlorophenyl) glutaric acid monoamide (CGM) from 3-(4-chlorophenyl) glutaric acid diamide (CGD) through stereoselective hydrolysis. (R)-CGM is a useful synthetic intermediate for arbaclofen. Methods and Results Four CGD-assimilating micro-organisms were found to be potential catalysts for (R)-CGM production. Among these micro-organisms, Comamonas sp. KNK3-7 (NITE BP-963) produced (R)-CGM with the highest optical purity [98·7% enantiomeric excess (e.e.)] and was selected as the most promising strain. In addition, Comamonas sp. KNK3-7 could asymmetrically hydrolyse 3-isobutyl glutaric acid diamide (IBD) to produce (R)-3-isobutyl glutaric acid monoamide [(R)-IBM] with high optical purity (>99·0% e.e.). Conclusion The synthesis of a (R)-3-substituted glutaric acid monoamide by desymmetrization of 3-substituted glutaric acid diamide with a micro-organism and an enzyme has not been previously reported. This finding indicates the possibility of the preparation of a variety of optically active 3-substituted glutaric acid monoamides using the amidase from Comamonas sp. KNK3-7. Significance and Impact of the Study The amidase from Comamonas sp. KNK3-7 may be useful for the chemoenzymatic synthesis of various kinds of chiral gamma-aminobutyric acids and may be used in a ‘green’ process to produce gamma-aminobutyric acids.

Aims To improve the efficiency of asymmetric hydrolysis of 3-(4-chlorophenyl) glutaric acid diamide (CGD) using a recombinant Comamonas sp. KNK3-7 amidase (CoAM) produced in Escherichia coli. Methods and Results The CoAM gene was cloned, sequenced, and found to comprise 1512 bp, encoding a polypeptide of 54,054 Da. CoAM-transformed E. coli were able to perform R-selective hydrolysis of CGD; however, complete conversion of 166.2 mmol l−1 CGD in 28 h could not be obtained. We attempted to optimize the reactivity of CoAM by mutating single amino acids in the substrate-binding domain. Notably, the methionine-substituted L146M mutant enzyme showed increased reactivity, completing the conversion of 166.2 mmol l−1 CGD in just 4 h. The Km value for L146M was lower than that of CoAM. Conclusions We succeeded in creating the L146M mutant of CoAM with increased substrate affinity and found that this was the best mutant for the hydrolysis of CGD. Significance and Impact of the Study Increasing the efficiency of hydrolysis of 3-substituted glutaric acid diamides is useful to improve the synthesis of optically active 3-substituted gamma-aminobutyric acid, used in the production of pharmacological drugs. This is the first report of efficient hydrolysis of CGD using amidase mutant-producing E. coli cells. This article is protected by copyright. All rights reserved.

The isolation and characterization of a gene (MALCE1) that encodes a fatty acid elongase from arachidonic acid-producing fungus Mortierella alpina 1S-4 are described. MALCE1 was confirmed to encode a fatty acid elongase by its expression in yeast Saccharomyces cerevisiae, resulting in the accumulation of 18-, 19-, and 20-carbon monounsaturated fatty acids and eicosanoic acid. Furthermore, the MALCE1 yeast transformant efficiently elongated exogenous 9-hexadecenoic acid, 9,12-octadecadienoic acid, and 9,12,15-octadecatrienoic acid. The MALCE1 gene-silenced strain obtained from M. alpina 1S-4 exhibited a low content of octadecanoic acid and a high content of hexadecanoic acid, compared with those in the wild strain. The enzyme encoded by MALCE1 was demonstrated to be involved in the conversion of hexadecanoic acid to octadecanoic acid, its main role in M. alpina 1S-4.

The recent use of optically active 3-substituted gamma-aminobutyric acid (GABA) analogs in human therapeutics has identified a need for an efficient, stereoselective method of their synthesis. Here, bacterial strains were screened for enzymes capable of stereospecific hydrolysis of 3-substituted glutarimides to generate (R)-3-substituted glutaric acid monoamides. The bacteria Alcaligenes faecalis NBRC13111 and Burkholderia phytofirmans DSM17436 were discovered to hydrolyze 3-(4-chlorophenyl) glutarimide (CGI) to (R)-3-(4-chlorophenyl) glutaric acid monoamide (CGM) with 98.1 % enantiomeric excess (e.e.) and 97.5 % e.e., respectively. B. phytofirmans DSM17436 could also hydrolyze 3-isobutyl glutarimide (IBI) to produce (R)-3-isobutyl glutaric acid monoamide (IBM) with 94.9 % e.e. BpIH, an imidase, was purified from B. phytofirmans DSM17436 and found to generate (R)-CGM from CGI with specific activity of 0.95 U/mg. The amino acid sequence of BpIH had a 75 % sequence identity to that of allantoinase from A. faecalis NBRC13111 (AfIH). The purified recombinant BpIH and AfIH catalyzed (R)-selective hydrolysis of CGI and IBI. In addition, a preliminary investigation of the enzymatic properties of BpIH and AfIH revealed that both enzymes were stable in the range of pH 6–10, with an optimal pH of 9.0, stable at temperatures below 40 °C, and were not metalloproteins. These results indicate that the use of this class of hydrolase to generate optically active 3-substituted glutaric acid monoamide could simplify the production of specific chiral GABA analogs for drug therapeutics.

Five mutants were obtained, Y11, Y135, Y164, Y180 and Y61, capable of accumulating higher amounts of arachidonic acid (AA) than Mortierella alpina 1S-4, an industrial strain for the production of AA-rich triacylglycerol (TG). This is thought to be due to low or no activity of n-3 desaturation with conversion of AA to eicosapentaenoic acid, which functions at a cultural temperature below 20°C. In small-scale cultivation under optimum conditions, Y11 and Y61 respectively accumulated 4.97 mg/ml and 4.11 mg/ml of AA, using a high concentration of glucose at 20°C, compared with 3.74 mg/ml for M. alpina 1S-4. In a 5-l jar fermentor, the AA content in Y11 and Y61 kept increasing during cultivation, with consumption of the glucose in the medium; and this reached 1.48 mg/ml and 1.77 mg/ml (118 mg/g, 120 mg/g of dry mycelia) at day 10, respectively, compared with 0.95 mg/ml (86 mg/g of dry mycelia) for M. alpina 1S-4. From the results of lipid analysis, the TG contents of Y11 and Y61 in the major lipids were significantly higher than that of M. alpina 1S-4; and the AA percentages in TG of Y11 and Y61 were also higher. Both Y11 and Y61 are potential producers of TG rich in AA.

The liverwort Marchantia polymorpha contains high proportions of arachidonic and eicosapentaenoic acids. In general, these C20 polyunsaturated fatty acids (PUFA) are synthesized from linoleic and alpha -linolenic acids, respectively, by a series of reactions catalyzed by Delta(6)-desaturase, an ELO-like enzyme involved in Delta(6) elongation and Delta(5)-desaturase. Here we report the isolation and characterization of the cDNAs, MpDES6, MpELO1 and MpDES5, coding for the respective enzymes from M. polymorpha. Co-expression of the MpDES6, MpELO1 and MpDES5 cDNAs resulted in the accumulation of arachidonic and eicosapentaenoic acids in the methylotrophic yeast Pichia pastoris. Interestingly, Delta(6) desaturation by the expression of the MpDES6 cDNA appears to occur both in glycerolipids and the acyl-CoA pool, although other lower-plant Delta(6)-desaturases are known to have a strong preference for glycerolipids.

Five mutants were obtained, Y11, Y135, Y164, Y180 and Y61, capable of accumulating higher amounts of arachidonic acid (AA) than Mortierella alpina 1S-4, an industrial strain for the production of AA-rich triacylglycerol (TG). This is thought to be due to low or no activity of n-3 desaturation with conversion of AA to eicosapentaenoic acid, which functions at a cultural temperature below 20 degrees C. In small-scale cultivation under optimum conditions, Y11 and Y61 respectively accumulated 4.97 mg/ml and 4.11 mg/ml of AA, using a high concentration of glucose at 20 degrees C, compared with 3.74 mg/ml for M. alpina 1S-4. In a 5-1 jar fermentor, the AA content in Y11 and Y61 kept increasing during cultivation, with consumption of the glucose in the medium; and this reached 1.48 mg/ml and 1.77 mg/ml (118 mg/g, 120 mg/g of dry mycelia) at day 10, respectively, compared with 0.95 mg/ml (86 mg/g of dry mycelia) for M. alpina 1S-4. From the results of lipid analysis, the TG contents of Y11 and Y61 in the major lipids were significantly higher than that of M. alpina 1S-4; and the AA percentages in TG of Y11 and Y61 were also higher. Both Y11 and Y61 are potential producers of TG rich in AA.