RESUMO
BAM is a conserved molecular machine, the central component of which is BamA. Orthologues of BamA are found in all Gram-negative bacteria, chloroplasts and mitochondria where it is required for the folding and insertion of ß-barrel containing integral outer membrane proteins (OMPs) into the outer membrane. BamA binds unfolded ß-barrel precursors via the five polypeptide transport-associated (POTRA) domains at its N-terminus. The C-terminus of BamA folds into a ß-barrel domain, which tethers BamA to the outer membrane and is involved in OMP insertion. BamA orthologues are found in all Gram-negative bacteria and appear to function in a species-specific manner. Here we investigate the nature of this species-specificity by examining whether chimeric Escherichia coliâ BamA fusion proteins, carrying either the ß-barrel or POTRA domains from various BamA orthologues, can functionally replace E. coliâ BamA. We demonstrate that the ß-barrel domains of many BamA orthologues are functionally interchangeable. We show that defects in the orthologous POTRA domains can be rescued by compensatory mutations within the ß-barrel. These data reveal that the POTRA and barrel domains must be precisely aligned to ensure efficient OMP insertion.
Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Proteínas de Escherichia coli/metabolismo , Bactérias Gram-Negativas/metabolismo , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Quimera/genética , Quimera/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Bactérias Gram-Negativas/genética , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Dobramento de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Especificidade da EspécieRESUMO
Human babesiosis data in Africa is scarce. The clinical presentation and parasite morphology mimics falciparum malaria infection. Diagnostic confirmation is informed by adequate history and communication with the laboratory to activate appropriate testing. This case report describes the course of a returning traveller with persisting symptoms that resolved on tailored antimicrobial therapy following prompt collaborative diagnosis. Contribution: Case highlighting overlapping characteristics of Babesia and malaria infection, necessitating close clinical and laboratory correlation to confirm diagnosis.
RESUMO
We have functionally produced the outer membrane cytochrome OmcA from Shewanella oneidensis in Escherichia coli. Substrate accessibility experiments indicate that OmcA is surface exposed in an E. coli B strain but not in a K-12 strain. We show that a functional type II secretion system is required for surface localization.