Abstract
Mycobacteria have low-permeability outer membranes that render them resistant to most antibiotics. Hydrophilic nutrients can enter by way of transmembrane-channel proteins called porins. An x-ray analysis of the main porin from Mycobacterium smegmatis, MspA, revealed a homooctameric goblet-like conformation with a single central channel. This is the first structure of a mycobacterial outer-membrane protein. No structure-related protein was found in the Protein Data Bank. MspA contains two consecutive beta barrels with nonpolar outer surfaces that form a ribbon around the porin, which is too narrow to fit the thickness of the mycobacterial outer membrane in contemporary models.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Arginine / chemistry
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Cell Membrane Permeability
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Cloning, Molecular
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Crystallization
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Crystallography, X-Ray
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Electric Conductivity
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Escherichia coli / genetics
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Hydrogen Bonding
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Hydrophobic and Hydrophilic Interactions
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Models, Molecular
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Molecular Sequence Data
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Mutation
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Mycobacterium smegmatis / chemistry*
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Mycobacterium smegmatis / metabolism
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Porins / chemistry*
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Porins / genetics
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Porins / metabolism
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Protein Conformation
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Protein Structure, Quaternary
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Recombinant Proteins / chemistry
Substances
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Porins
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Recombinant Proteins
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mspA protein, Mycobacterium smegmatis
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Arginine