Biochemical and structural study of the homologues of the thiol-disulfide oxidoreductase DsbA in Neisseria meningitidis.

Bacterial virulence depends on the correct folding of surface-exposed proteins, a process catalyzed by the thiol-disulfide oxidoreductase DsbA, which facilitates the synthesis of disulfide bonds in Gram-negative bacteria. The Neisseria meningitidis genome possesses three genes encoding active DsbAs: DsbA1, DsbA2 and DsbA3. DsbA1 and DsbA2 have been characterized as lipoproteins involved in natural competence and in host interactive biology, while the function of DsbA3 remains unknown.

DHR51, the Drosophila melanogaster homologue of the human photoreceptor cell-specific nuclear receptor, is a thiolate heme-binding protein.

Heme has been recently described as a regulating ligand for the activity of the human nuclear receptors (NR) REV-ERBalpha and REV-ERBbeta and their Drosophila homologue E75. Here, we report the cloning, expression in Escherichia coli, purification, and screening for the heme-binding ability of 11 NR ligand-binding domains of Drosophila melanogaster (DHR3, DHR4, DHR39, DHR51, DHR78, DHR83, HNF4, TLL, ERR, FTZ-F1, and E78), of unknown structure. One of these NRs, DHR51, homologous to the human photoreceptor cell-specific nuclear receptor (PNR), specifically binds heme and exhibits a UV-visible spectrum identical to that of heme-bound E75-LBD.

Drosophila nuclear receptor E75 is a thiolate hemoprotein.

Drosophila E75 is a member of the nuclear receptor superfamily. These eukaryotic transcription factors are involved in almost all physiological processes. They regulate transcription in response to binding of rigid hydrophobic hormone ligands.