Identification of transporters driving nutrient uptake in marine diatoms

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K15326
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Aquatic life science
• Research Institution: Kwansei Gakuin University
• Principal Investigator: Tsuji Yoshinori 関西学院大学, 理工学部, 助教 (40728268)
• Research Collaborator: Matsuda Yusuke ; Nakajima Kensuke
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: 海洋性珪藻 / 光合成 / CO2固定 / CO2濃縮機構 / 海洋物質循環

Outline of Final Research Achievements

Marine diatoms operate active CO2-concentrating mechanism, by which cells can actively incorporate and fix dissolved inorganic carbon (DIC). In the pennate diatom Phaeodactylum tricornutum, solute carrier 4 (SLC4) type transporters are involved in the uptake of DIC across plasma membrane. While SLC4 is considered to mediate Na+-HCO3- co-transport, the mechanism to maintain Na+ gradient across plasma membrane have been unknown. In this study, I searched for candidates of plasma membrane transporters involved in the maintenance of Na+-gradient in diatoms. Affinity of cells for DIC was decreased by treating vanadate, an inhibitor of P-type ATPase, suggesting that P-type ATPase such as Na+/K+ pump is involved in the sodium-dependent DIC uptake. To identify major plasma membrane proteins, cell surface proteins were labeled by impermeable biotinylation reagent, and several proteins were successfully labeled by biotin.

Free Research Field

植物代謝生理学

Academic Significance and Societal Importance of the Research Achievements

珪藻による栄養塩の吸収と同化は、地球規模の物質循環を駆動するエンジンとして機能している。本研究では、栄養塩吸収の駆動力を生み出すと推定されているナトリウムポンプの分子実体同定を目指した。その結果、哺乳類などでナトリウム排出に関与することが知られている輸送体（P型ATPase）が、珪藻の栄養塩吸収に関与することを示唆した。また、珪藻の細胞表層タンパク質を網羅的に同定するための基盤も確立した。これらの結果は、珪藻による栄養塩吸収機構と物質生産の理解に必要不可欠なものである。