Rhamnogalacturonan degradation mechanism of Aspergillus nidulans

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05815
• 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: Meijo University
• Principal Investigator: Shimizu Motoyuki 名城大学, 農学部, 准教授 (20423535)
• Co-Investigator(Kenkyū-buntansha): 高須賀 太一 北海道大学, 農学研究院, 准教授 (70748409)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: Aspergillus nidulans / pectin / rhamnogalacturonan lyase

Outline of Final Research Achievements

Hypothetical proteins (HPs) were produced by Aspergillus nidulans grown with pectin as a sole carbon source. Among them, we identified a novel rhamnogalacturonan (RG) lyase (AnRGL) with no similarity to any described functional proteins and no putative conserved domains. AnRGL showed significant activity toward RG, while acitivity toward polygalacturonic acid, α-1, 5-arabinan, arabinogalactan, and β-1, 4 -galactan, which are components of pectin, were not detectable. RG degradation products by AnRGL were analyzed using MALDI-TOF-MS. RG oligosaccharides containing unsaturated bonds were identified. These results indicate that AnRGL is a novel RG lyase that belongs to a new polysaccharide lyase (PL) family. The crystal structure of AnRGL was solved at a resolution of 1.72 A, and AnRGL is a β-helix structure.

Free Research Field

応用微生物学

Academic Significance and Societal Importance of the Research Achievements

ペクチンの分解で生じるオリゴ糖（D-ガラクトシル-β-1,4-ラムノース）を炭素源として、ビフィズス菌Bifidobacterium infantisと難病の偽膜性腸炎原因菌Clostridium difficileを共培養したところ、C. difficileの増殖を抑えることが報告されており、応用研究にも波及効果が期待できる。
本研究により見出された糸状菌由来のペクチン分解酵素の利用によって、ペクチンを多く含む果皮などの未利用植物資源から新規機能性オリゴ糖を生産することが可能になり、上記のような疾病予防効果を通じて、人類の健康に貢献できる。