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動植物の双方で重要な役割を果たすイオン輸送体CLC familyの研究者であるAccardi

2009年7月27日(月) 10:30-12:00
東京理科大学 野田キャンパス 計算科学研究センター 4階大会議室

講師: Dr. Alessio Accardi
(Assistant Professor&s_comma; Department of Molecular Physiology and Biophysics&s_comma;
College of Medicine&s_comma; University of Iowa&s_comma; U.S.A.)

演題:“Evolutionary conservation of ionic transport&s_comma; binding and
selectivity in human&s_comma; plant and bacterial ion channels and transporters”

Ion binding to a secondary active transporter triggers a cascade of
conformational rearrangements resulting in substrate translocation across
cellular membranes. Despite the fundamental role of this step&s_comma; direct
measurements of binding to transporters have been possible only rarely. We
investigated the molecular and thermodynamic bases of ion binding and
selectivity in the prototypical H+/Cl-exchanger CLC-ec1&s_comma; a bacterial
homologue of the CLC family of Cl- channels and transporters. Cl- binding
strongly depends on the conformational state of the protein. Cl- affinity is
highest with the extracellular gate removed&s_comma; and progressively weakens as
the transporter adopts the occluded configuration and then with the
intracellular gate removed. We found that the central ion-binding site
determines selectivity in the CLC transporters and channels from bacteria to
plants and animals. We were able to confer plant-like specificity for NO3-
upon the otherwise Cl- specific CLC-ec1 transporter and CLC-0 channel. Our
results suggest that the CLC transporters operate through an affinity
switch mechanism and that the molecular bases of substrate specificity are
evolutionarily conserved in the channels and transporters of the CLC family.

朽津 和幸 (Professor Dr. Kazuyuki KUCHITSU)
東京理科大学 理工学部 応用生物科学科
文部科学省 研究振興局 学術調査官
(生物学・農学担当 プログラムオフィサー) 併任
〒278-8510 千葉県野田市山崎2641
e-mail: kuchitsu@rs.noda.tus.ac.jp
FAX: 04-7123-9767