title: Is Ffh required for export of secretory proteins?
abstract: In Escherichia coli, protein export from the cytoplasm may occur via the signal recognition particle (SRP)-dependent pathway or the Sec-dependent pathway. Membrane proteins utilize the SRP-dependent route, whereas many secretory proteins use the cytoplasmic Sec machinery. To examine the possibility that signal peptide hydrophobicity governs which targeting route is utilized, we used a series of PhoA signal sequence mutants which vary only by incremental hydrophobicity changes. We show that depletion of SRP, but not trigger factor, affects all the mutants examined. These results suggest secretory proteins with a variety of signal sequences, as well as membrane proteins, require SRP for export.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3044, USA.
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Rusch
authors.forename: J
authors.initials: J
authors.lastname: Luirink
authors.forename: D A
authors.initials: DA
authors.lastname: Kendall
mesh_terms: D000469:Alkaline Phosphatase; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism; D018844:Cyclin-Dependent Kinases; D003593:Cytoplasm / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D019696:Peptidylprolyl Isomerase / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D017386:Sequence Homology, Amino Acid; D018271:Signal Recognition Particle / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D018271:Signal Recognition Particle; D018844:Cyclin-Dependent Kinases; D000469:Alkaline Phosphatase; C114089:phoA protein, E coli; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase