Abstract
In Gram-negative bacteria, a wide variety of virulence factors are secreted via the autotransporter (AT) pathway. Intriguingly, there is no significant concentration of ATP in the periplasm, nor a proton gradient across the OM, so the energetic origin of efficient secretion of AT proteins is unknown. More than 97% of AT proteins are predicted to contain right-handed parallel beta-helical structure, and the three crystal structures available for AT passenger domains each contain a long right-handed parallel beta-helix. Previous studies have shown that pertactin, an AT from Bordetella pertussis, exhibits three-state folding and has a C-terminal stable core structure. Here, we show that Pet, an unrelated AT from Escherichia coli, also exhibits three-state unfolding and also has a stable core structure. Deletion mutants, mass spectrometry, and N-terminal sequencing demonstrate that the Pet stable core is also located near the C-terminus of the passenger domain. Moreover, sequence analysis suggests that three-state folding and a C-terminal stable core structure could be important general features of the biogenesis of AT proteins in vivo.
Publication types
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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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Amino Acid Sequence
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Bacterial Outer Membrane Proteins / chemistry
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Bacterial Outer Membrane Proteins / genetics
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Bacterial Toxins / chemistry*
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Bacterial Toxins / genetics
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Conserved Sequence
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Electrophoresis, Polyacrylamide Gel
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Endopeptidase K / chemistry
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Enterotoxins / chemistry*
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Enterotoxins / genetics
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Escherichia coli / chemistry
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / genetics
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Guanidine / chemistry
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Models, Molecular
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Molecular Sequence Data
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Protein Denaturation
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Protein Folding*
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Sequence Alignment
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Serine Endopeptidases
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Virulence Factors / chemistry*
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Virulence Factors / genetics
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Virulence Factors, Bordetella / chemistry
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Virulence Factors, Bordetella / genetics
Substances
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Bacterial Outer Membrane Proteins
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Bacterial Toxins
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Enterotoxins
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Escherichia coli Proteins
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Virulence Factors
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Virulence Factors, Bordetella
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pertactin
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heat-labile enterotoxin, E coli
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Pet protein, E coli
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Serine Endopeptidases
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Endopeptidase K
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Guanidine