Abstract
We detect internal water molecules in a membrane-embedded receptor-transducer complex and demonstrate water structure changes during formation of the signaling state. Time-resolved FTIR spectroscopy reveals stimulus-induced repositioning of one or more structurally active water molecules to a significantly more hydrophobic environment in the signaling state of the sensory rhodopsin II (SRII)-transducer (HtrII) complex. These waters, distinct from bound water molecules within the SRII receptor, appear to be in the middle of the transmembrane interface region near the Tyr199(SRII)-Asn74(HtrII) hydrogen bond. We conclude that water potentially plays an important role in the SRII --> HtrII signal transfer mechanism in the membrane's hydrophobic core.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Archaeal Proteins / chemistry*
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Archaeal Proteins / metabolism
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Cell Membrane / chemistry*
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Cell Membrane / metabolism
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Halorhodopsins / chemistry*
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Halorhodopsins / metabolism
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Hydrophobic and Hydrophilic Interactions
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Protein Binding / physiology
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Protein Interaction Domains and Motifs / physiology*
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Sensory Rhodopsins / chemistry*
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Sensory Rhodopsins / metabolism
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Signal Transduction / physiology*
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Spectroscopy, Fourier Transform Infrared
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Water / chemistry*
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Water / metabolism
Substances
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Archaeal Proteins
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Halorhodopsins
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HtrII protein, Halobacterium salinarium
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Sensory Rhodopsins
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sensory rhodopsin II protein, archaeal
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Water