Elucidation of the function and biosynthetic mechanism of the cell wall polysaccharide Nigeran of Aspergillus luchuensis

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K15737
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: University of the Ryukyus
• Principal Investigator: Uechi Keiko 琉球大学, 農学部, 助教 (70733426)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: ニゲラン / α-1,3-グルカン / 真菌細胞壁 / Aspergillus属

Outline of Final Research Achievements

The fungal cell wall is composed mainly of polysaccharides. Under nitrogen-free conditions, some Aspergillus spp. produce significant levels of nigeran, a fungal cell wall polysaccharide composed of alternating a-1,3/1,4-glucosidic linkages. The mechanisms regulating the biosynthesis and function of nigeran are unknown. Here, we performed RNA sequencing of Aspergillus luchuensis cultured under nitrogen-free or low-nitrogen conditions. A putative a-1,3-glucan synthase gene, whose transcriptional level was upregulated under nitrogen-free conditions, was demonstrated to encode nigeran synthase. Furthermore, two genes encoding an a-glucanotransferase and a hypothetical protein were shown to be involved in controlling the nigeran content and molecular weight.

Free Research Field

応用微生物

Academic Significance and Societal Importance of the Research Achievements

本研究では，糸状菌のニゲラン合成酵素遺伝子をはじめて同定した。本酵素はα-1,3-グルカン合成酵素との相同性が高く，酵素化学的な多糖合成メカニズムはほぼ同様だと推定される。α-1,3-グルカンは真菌が宿主への病原性を発揮するための重要な構成成分であることから医学的な関心も高い。ニゲランはα-1,3-グルカンよりも容易に抽出できることから，ニゲラン合成研究で得た知見は，α-1,3-グルカン合成についても応用できることが期待される。また，ニゲランは新規のバイオマスベースプラスチック素材としての利用も期待できる。