Molecular Mechanism and Applications of Rare Earth Elements-Dependent Stimulation in Microbial Production of Stereo-Regular (Homochiral) Poly-gamma-Glutamate as Novel Extremolyte-Like Materials

2022 Fiscal Year Final Research Report

• Project/Area Number: 17H03796
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied microbiology
• Research Institution: Kochi University
• Principal Investigator: Ashiuchi Makoto 高知大学, 教育研究部総合科学系生命環境医学部門, 教授 (20271091)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 超広域環境微生物 / 環境適応因子 / ポリγグルタミン酸 / レアメタル（レアアース）バイオロジー / バイオツール化

Outline of Final Research Achievements

We have been conducting computational chemistry focusing on the untranslated regions responsible for the regulation of PGA synthesis gene expression in Bacillus megaterium and Bacillus natto, and B. megaterium has a special nucleotide sequence harboring a riboswitch-like structure, which is adjacent to the the global regulator (DegU)-recognition site. An inhibitory-PCR method was hence devised to examine the effects of rare earths on higher functions and structures of the regulatory region (Cap/5'-UTR) (nullification of the attenuation mechanism, selectivity for heavy rare earth elements, and so on). DegU was analyzed by "gel shift assay". As a result, it was found that the combination of the abiotic metal species (Dy) and the post-translationally modified protein (DegU-P) controls the binding behavior with a specific DNA sequence.

Free Research Field

応用分子微生物学

Academic Significance and Societal Importance of the Research Achievements

堆肥から深海底までの地球環境に高度の適応した土壌細菌“巨大菌”にレアアース（特にジスプロシウム）を与えつつ培養すると、優位に増殖速度が増加することに加え、ＰＧＡと呼ばれる有用バイオポリマーの生細胞当たりの生産能まで増大するという画期的な応答現象を発見した。レアアースは重金属であることから、生物応答に関しては毒性や代謝抑制ありきの解析に焦点が絞られる中、本発見は生物と重金属の新たな接点に焦点を当てる千載一遇の機会と理解した。本研究成果は遺伝子発現制御を司る新たな構造モチーフの発見を介した基礎分子微生物学の発展に繋がるとともに、有価レアアースの高感度識別や探索に向けた応用展開にも期待が持てる。