Metabolic pathways leading from amino acids to vitamin B₁₂ in Propionibacterium shermanii, and the sources of the seven methyl carbons

Abstract

The metabolic pathways leading from l‐[2‐13C]aspartic acid, [2‐13C]glycine and l‐[methyl‐13C]methionine to vitamin B12 were investigated, focusing on the biosynthetic pathways leading to the aminopropanol moiety of vitamin B12 and on the role of the Shemin pathway leading to δ‐aminolevulinic acid (a biosynthetic intermediate of tetrapyrrole), by means of feeding experiments with Propionibacterium shermanii in combination with 13C‐NMR spectroscopy. The 13C‐methylene carbons of l‐[2‐13C]aspartic acid, which is transformed to [2‐13C]glycine via l‐[2‐13C]threonine, and [2‐13C]glycine added to the culture medium served mainly to enrich the seven methyl carbons of the corrin ring through C‐methylation by S‐adenosyl‐l‐[methyl‐13C]methionine derived from catabolically generated l‐[methyl‐13C]methionine in the presence of tetrahydrofolic acid. The results indicate that the catabolism of these amino acids predominates over pathways leading to (2R)‐1‐amino‐2‐propanol or δ‐aminolevulinic acid in P. shermanii. Feeding of l‐[methyl‐13C]methionine efficiently enriched all seven methyl carbons. In the cases of [2‐13C]glycine and l‐[methyl‐13C]methionine, the 13C‐enrichment ratio of the methyl carbon at C‐25 (the site of the first C‐methylation) was less than those of the other six methyl carbons, probably due to the influence of endogenous d‐glucose in P. shermanii. The almost identical 13C‐enrichment ratios of the other six methyl carbons indicated that these C‐methylations during vitamin B12 biosynthesis were completed before the amino acids were completely consumed. However, in the case of l‐[2‐13C]aspartic acid, the 13C‐enrichment ratios of five methyl carbons were low and similar, whereas the last two sites of C‐methylation (C‐53 and C‐35) were not labeled, presumably because of complete consumption of the smaller amount of added label. The ratios of 13C‐incorporation into the seven methyl carbons are influenced by the conditions of amino acid feeding experiments in a manner that is dependent upon the order of C‐methylation in the corrin ring of vitamin B12.

Multiomics Approach to Explore the Amelioration Mechanisms of Glucomannans on the Metabolic Disorder of Type 2 Diabetic Rats

“…Also, aspartic acid, arginine, citrulline, and ornithine are involved in the urea cycle, and the increase of these amino acids may responsible for the high levels of urea in diabetic rats (Table S6 of the Supporting Information) . In addition, amino acid catabolites could be the precursor of vitamin biosynthesis, such as catabolism of aspartic acid, methionine, and glycine, which could provide carbon for vitamin B 12 biosynthesis, which plays an important role in various biological processes, such as protein metabolism, promoting the cell growth and reproduction, etc. (Figure H). , The increased BCAAs were found positively correlated with metabolic disorder, including obesity, insulin resistance, and decreased leptin secretion .…”

Efficient syntheses of benzyl and n‐octyl [1,3‐13C2]acetoacetates, and their application to syntheses of 13C‐labelled pyrrole and 13C‐labelled hymecromone

“…The residue was dried and dissolved in CHCl 3 . The solution was filtered, and the filtrate was evaporated to give dibenzyl 2,4-dimethyl [2,4- [2,4-13 C 2 ]Hymecromone (6) (7-Hydroxy-4-methyl [2,[4][5][6][7][8][9][10][11][12][13]…”

“…For example, we have previously investigated vitamin B 12 biosynthesis and phenacetin metabolism by using d-aminolevulinic acid (a biosynthetic intermediate of tetrapyrrole), L-aspartic acid or phenacetin regioselectively labelled with 13 C. [1][2][3] Therefore, efficient 13 C-labelling synthetic methods are required. We have obtained various 13 C-labelled compounds by using […”

“…Introduction 13 C-Labelled compounds are useful for tracer studies in life science research. For example, we have previously investigated vitamin B 12 biosynthesis and phenacetin metabolism by using d-aminolevulinic acid (a biosynthetic intermediate of tetrapyrrole), L-aspartic acid or phenacetin regioselectively labelled with 13 C. [1][2][3] Therefore, efficient 13 C-labelling synthetic methods are required. We have obtained various 13 C-labelled compounds by using [ 13 C]urea as the 13 C-source, 4 and we considered it important to develop efficient syntheses of a range of 13 C-labelled units that could be used to prepare various 13 Clabelled compounds.…”