title: A conserved stable core structure in the passenger domain beta-helix of autotransporter virulence proteins.
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.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Renn
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Clark
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics; D017124:Conserved Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D019286:Endopeptidase K / Q000737:chemistry; D004768:Enterotoxins / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D019791:Guanidine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012697:Serine Endopeptidases; D037521:Virulence Factors / Q000737:chemistry* / Q000235:genetics; D010566:Virulence Factors, Bordetella / Q000737:chemistry / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D037521:Virulence Factors; D010566:Virulence Factors, Bordetella; C068929:pertactin; C027538:heat-labile enterotoxin, E coli; C530786:Pet protein, E coli; D012697:Serine Endopeptidases; D019286:Endopeptidase K; D019791:Guanidine