Identification and characterization of an Escherichia coli gene required for the formation of correctly folded alkaline phosphatase, a periplasmic enzyme.
Tn5 insertion mutations of Escherichia coli were isolated that impaired the formation of correctly folded alkaline phosphatase (PhoA) in the periplasm. The PhoA polypeptide synthesized in the mutants was translocated across the cytoplasmic membrane but not released into the periplasmic space. It was susceptible to degradation by proteases in vivo and in vitro. The wild-type counterpart of this gene (named ppfA) has been sequenced and shown to encode a periplasmic protein with a pair of potentially redox-active cysteine residues. PhoA synthesized in the mutants indeed lacked disulfide bridges. These results indicate that the folding of PhoA in vivo is not spontaneous but catalyzed at least at the disulfide bond formation step.
Kamitani
S
S
Department of Cell Biology, Kyoto University, Japan.
Akiyama
Y
Y
Ito
K
K
D000469:Alkaline Phosphatase / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology*; D002874:Chromosome Mapping; D004220:Disulfides; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011487:Protein Conformation; D016364:Reading Frames; D014357:Trypsin / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004220:Disulfides; D000469:Alkaline Phosphatase; D014357:Trypsin