{'fraction_non_alphanumeric': 0.023537803138373753, 'fraction_numerical': 0.011412268188302425, 'mean_word_length': 5.680952380952381, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
TP0453, a Concealed Outer Membrane Protein of Treponema pallidum, Enhances Membrane Permeability

ABSTRACT The outer membrane of Treponema pallidum, the noncultivable agent of venereal syphilis, contains a paucity of protein(s) which has yet to be definitively identified. In contrast, the outer membranes of gram-negative bacteria contain abundant immunogenic membrane-spanning β-barrel proteins mainly involved in nutrient transport. The absence of orthologs of gram-negative porins and outer membrane nutrient-specific transporters in the T. pallidum genome predicts that nutrient transport across the outer membrane must differ fundamentally in T. pallidum and gram-negative bacteria. Here we describe a T. pallidum outer membrane protein (TP0453) that, in contrast to all integral outer membrane proteins of known structure, lacks extensive β-sheet structure and does not traverse the outer membrane to become surface exposed. TP0453 is a lipoprotein with an amphiphilic polypeptide containing multiple membrane-inserting, amphipathic α-helices. Insertion of the recombinant, nonlipidated protein into artificial membranes results in bilayer destabilization and enhanced permeability. Our findings lead us to hypothesize that TP0453 is a novel type of bacterial outer membrane protein which may render the T. pallidum outer membrane permeable to nutrients while remaining inaccessible to antibody.