Two cysteines in each periplasmic domain of the membrane protein DsbB are required for its function in protein disulfide bond formation.
DsbB is a protein component of the pathway that leads to disulfide bond formation in periplasmic proteins of Escherichia coli. Previous studies have led to the hypothesis that DsbB oxidizes the periplasmic protein DsbA, which in turn oxidizes the cysteines in other periplasmic proteins to make disulfide bonds. Gene fusion approaches were used to show that (i) DsbB is a membrane protein which spans the membrane four times and (ii) both the N- and C-termini of the protein are in the cytoplasm. Mutational analysis shows that of the six cysteines in DsbB, four are necessary for proper DsbB function in vivo. Each of the periplasmic domains of the protein has two essential cysteines. The two cysteines in the first periplasmic domain are in a Cys-X-Y-Cys configuration that is characteristic of the active site of other proteins involved in disulfide bond formation, including DsbA and protein disulfide isomerase.
Department of Microbiology, Harvard Medical School, Boston, MA 02115.
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D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism*; D002876:Chromosomes, Bacterial; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004220:Disulfides / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D004220:Disulfides; C079503:DsbB protein, Bacteria; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D000469:Alkaline Phosphatase; D001616:beta-Galactosidase; D003545:Cysteine