Helicity, membrane incorporation, orientation and thermal stability of the large conductance mechanosensitive ion channel from E. coli.
In this report, we present structural studies on the large conductance mechanosensitive ion channel (MscL) from E. coli in detergent micelles and lipid vesicles. Both transmission Fourier transform infrared spectroscopy and circular dichroism (CD) spectra indicate that the protein is highly helical in detergents as well as liposomes. The secondary structure of the proteins was shown to be highly resistant towards denaturation (25-95 degrees C) based on an ellipticity thermal profile. Amide H+/D+ exchange was shown to be extensive (ca. 66%), implying that two thirds of the protein are water accessible. MscL, reconstituted in oriented lipid bilayers, was shown to possess a net bilayer orientation using dichroic ratios measured by attenuated total-reflection Fourier transform infrared spectroscopy. Here, we present and discuss this initial set of structural data on this new family of ion-channel proteins.
Arkin
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Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
Sukharev
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Blount
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P
Kung
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C
Brünger
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AT
D001426:Bacterial Proteins / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D006358:Hot Temperature; D007473:Ion Channels / Q000737:chemistry*; D008051:Lipid Bilayers; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; C086596:MscL protein, E coli