Studies on novel functions of D-branched-chain amino acids (D-BCAA) in lactic acid bacteria

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K05412
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: Akita Prefectural University
• Principal Investigator: Mutaguchi Yuta 秋田県立大学, 生物資源科学部, 助教 (30724314)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: D-amino acid / BCAA / lactic acid bacteria / racemase / epimerase / transporter / permease

Outline of Final Research Achievements

In this study, it was revealed that the lactic acid bacteria, isolated from human body and foods, have a novel enzyme “isoleucine 2-epimerase”gene in their genome. Therefore, it is suggested that the observation of the physiological functions of D-branched-chain amino acids produced by this enzyme in lactic acid bacteria would be applied to the medical and food fields. In addition, we revealed that the expressed protein from the putative amino acid transporter gene, adjacent to isoleucine 2-epimerase gene on Lentilactobacillus buchneri JCM 1115 genome, has L- and D-branched-chain amino acids uptake activity. This is the first example of amino acid transporter that shows the activity against D-branched-chain amino acids, not only for lactic acid bacteria, but also whole microbial research.

Free Research Field

酵素化学

Academic Significance and Societal Importance of the Research Achievements

ヒト常在乳酸菌や食品関連乳酸菌にイソロイシン2-エピメラーゼの存在を確認したことで、本酵素によって生産されると考えられるD-分岐鎖アミノ酸の乳酸菌における生理的意義を解明することができれば、その成果が医療や食品分野に応用できる可能性が示唆された。また、D-分岐鎖アミノ酸の細胞内への取込み活性をもつ膜タンパク質は、これまでに報告例がなく、本研究成果は乳酸菌に限らず、微生物研究全体においても学術的に新規性の高いものである。