RESUMO
Insertion of folded proteins into the outer membrane of Gram-negative bacteria is mediated by the essential ß-barrel assembly machine (Bam). Here, we report the native structure and mechanism of a core component of this complex, BamE, and show that it is exclusively monomeric in its native environment of the periplasm, but is able to adopt a distinct dimeric conformation in the cytoplasm. BamE is shown to bind specifically to phosphatidylglycerol, and comprehensive mutagenesis and interaction studies have mapped key determinants for complex binding, outer membrane integrity and cell viability, as well as revealing the role of BamE within the Bam complex.
Assuntos
Proteínas da Membrana Bacteriana Externa/química , Proteínas de Escherichia coli/química , Proteínas Mutantes/química , Conformação Proteica , Proteínas da Membrana Bacteriana Externa/genética , Sítios de Ligação , Proteínas de Escherichia coli/genética , Espectroscopia de Ressonância Magnética , Mutagênese Sítio-Dirigida , Proteínas Mutantes/genética , Proteínas Periplásmicas/química , Proteínas Periplásmicas/genética , Fosfatidilgliceróis/química , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genéticaRESUMO
Previous research shows that people with high self-esteem cope with threats to the self by reducing the extent to which their self-worth is contingent on the threatened domain (Buckingham, Weber, & Sypher, 2012). The present studies tested the hypothesis that this is a defensive process. In support of this hypothesis, Study 1 (N = 160), showed that self-affirmation attenuates the tendency for people with high self-esteem to reduce their contingencies of self-worth following self-threat. Furthermore, Study 2 (N = 286), showed that this tendency was more prevalent among people with defensive self-esteem than among those with secure self-esteem. The present studies imply that reducing contingent self-worth after self-threat is a defensive process. We discuss implications for theories of contingent self-worth.