22.01.2015 |
Dato | tor 29 jan |
Tid | 12:15 — 13:00 |
Sted | Aud. 6, building 1170, 3rd floor, Dept. Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus |
Lecture on "Structural basis for Ca2+-activation in TMEM16 chloride channels and lipid scramblases"
By Raimund Dutzler
Department of Biochemistry
University of Zurich
When: Friday 29 January 2015 at 12.15 - 13.00
Where: Aud. 6, building 1170, 3rd floorDept. Biomedicine, Aarhus University, Ole Worms Allé 3, 8000 Aarhus
Speaker host: Poul Nissen, DANDRITE
Abstract
The TMEM16 proteins (or Anoctamins) feature a remarkable functional diversity. They contain the long sought-after Ca2+-activated chloride channels but also lipid scramblases. We have determined the crystal structure of nhTMEM16, a fungal family member that operates as a Ca2+-activated lipid scramblase. Each subunit of the homodimeric protein contains ten transmembrane helices and a hydrophilic membrane-traversing cavity that is exposed to the lipid bilayer as a potential site of catalysis. This cavity harbors a conserved Ca2+-binding site located within the hydrophobic core of the membrane. Mutations of residues involved in Ca2+ coordination affect both, lipid scrambling in nhTMEM16 and gating in the Cl--channel TMEM16A. The nhTMEM16 structure thus reveals the general architecture of the family and its mode of Ca2+-activation. It also provides insight into potential scrambling mechanisms and serves as a framework to unravel the conduction of ions in certain TMEM16 proteins.