title: SecA-dependence of the translocation of a large periplasmic loop in the Escherichia coli MalF inner membrane protein is a function of sequence context.
abstract: We have analysed the translocation of a large periplasmic loop in the Escherichia coli MalF inner membrane protein when placed in different sequence contexts and under conditions when the function of the SecA protein is inhibited. The results show that the degree of SecA-dependence varies with sequence context: while translocation of the large loop in its normal context is only minimally affected by SecA inhibition, translocation is much more sensitive to SecA inhibition when the loop is placed in the context of other inner membrane proteins. Conversely, when the large MalF loop is replaced by segments from other proteins, translocation of those segments is again very sensitive to SecA inhibition. Thus, SecA-dependence is not an all-or-none phenomenon and is not only a simple function of, e.g. the length of a translocated segment or the hydrophobicity of the flanking transmembrane segments.
authors.affiliation: Karolinska Institute Center for Structural Biochemistry, NOVUM, Huddinge, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Sääf
authors.forename: H
authors.initials: H
authors.lastname: Andersson
authors.forename: G
authors.initials: G
authors.lastname: Gafvelin
authors.forename: G
authors.initials: G
authors.lastname: von Heijne
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D010450:Endopeptidases / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D017384:Sequence Deletion; D012697:Serine Endopeptidases
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D011993:Recombinant Fusion Proteins; D000069816:SEC Translocation Channels; C461599:maltose transport system, E coli; D010450:Endopeptidases; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins