title: Conditions leading to secretion of a normally periplasmic protein in Escherichia coli.
abstract: The phosphate-binding protein (PhoS) is a periplasmic protein which is part of the high-affinity phosphate transport system of Escherichia coli. Hyperproduction of PhoS in strains carrying a multicopy plasmid containing phoS led to partial secretion of the protein. By 6 h after transfer to phosphate-limiting medium, about 13% of the total newly synthesized PhoS was secreted to the medium. Kinetic studies demonstrated that this secretion consists of newly synthesized PhoS. This secretion occurs in PhoS-hyperproducer strains but not in a PhoS-overproducer strain. Another type of secretion concerning periplasmic PhoS was observed in both PhoS-hyperproducer and PhoS-overproducer strains. This mode of secretion depended upon the addition of phosphate to cells previously grown in phosphate-limiting medium.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism*; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism; D010957:Plasmids
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D028044:Phosphate-Binding Proteins; D010710:Phosphates