title: Thirty-three amino acids of the mature moiety of an unprocessed maltose-binding protein are sufficient for export in Escherichia coli.
abstract: Maltose-binding protein (MBP) is translocated across the cytoplasmic membrane of Escherichia coli; successful export depends on information in both the signal peptide and the mature moiety of the protein. To determine the shortest portion of the mature region that would maintain detectable entry of MBP into the export pathway, we took advantage of the properties of an MBP species with proline substituted in the +1 position relative to the cleavage site (MBP27-P). This protein efficiently crosses the cytoplasmic membrane but is not processed and acts as a competitive inhibitor of signal peptidase I (leader peptidase). Export of MBP27-P is measured by the inhibition of processing of other proteins, such as ribose-binding protein (RBP). A series of truncated derivatives of MBP27-P were tested for the ability to inhibit processing of RBP. An MBP27-P species with only 33 amino acids of the mature moiety inhibited processing of RBP, indicating that this truncated polypeptide was probably exported and interacted with signal peptidase I.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill 27599-7290.
authors.forename: G A
authors.initials: GA
authors.lastname: Barkocy-Gallagher
authors.forename: J G
authors.initials: JG
authors.lastname: Cannon
authors.forename: P J
authors.initials: PJ
authors.lastname: Bassford
mesh_terms: D018528:ATP-Binding Cassette Transporters; D001692:Biological Transport / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D021382:Protein Sorting Signals; C028003:RbsB protein, E coli; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli