Details

Autor(en) / Beteiligte

• Lórenz-Fonfría, Víctor A.
• Bamann, Christian
• Resler, Tom
• Schlesinger, Ramona
• Bamberg, Ernst
• Heberle, Joachim

Titel

Temporal evolution of helix hydration in a light-gated ion channel correlates with ion conductance

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2015-10, Vol.112 (43), p.E5796-E5804

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2015

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The discovery of channelrhodopsins introduced a new class of light-gated ion channels, which when genetically encoded in host cells resulted in the development of optogenetics. Channelrhodopsin-2 fromChlamydomonas reinhardtii, CrChR2, is the most widely used optogenetic tool in neuroscience. To explore the connection between the gating mechanism and the influx and efflux of water molecules inCrChR2, we have integrated light-induced time-resolved infrared spectroscopy and electrophysiology. Cross-correlation analysis revealed that ion conductance tallies with peptide backbone amide I vibrational changes at 1,665(−) and 1,648(+) cm−1. These two bands report on the hydration of transmembrane α-helices as concluded from vibrational coupling experiments. Lifetime distribution analysis shows that water influx proceeded in two temporally separated steps with time constants of 10 μs (30%) and 200 μs (70%), the latter phase concurrent with the start of ion conductance. Water efflux and the cessation of the ion conductance are synchronized as well, with a time constant of 10 ms. The temporal correlation between ion conductance and hydration of helices holds for fast (E123T) and slow (D156E) variants ofCrChR2, strengthening its functional significance.