Translocation of N-terminal tails across the plasma membrane.
Previously we have shown that the first hydrophobic domain of leader peptidase (lep) can function to translocate a short N-terminal 18 residue antigenic peptide from the phage Pf3 coat protein across the plasma membrane of Escherichia coli. We have now examined the mechanism of insertion of N-terminal periplasmic tails and have defined the features needed to translocate these regions. We find that short tails of up to 38 residues are efficiently translocated in a SecA- and SecY-independent manner while longer tails are very poorly inserted. Efficient translocation of a 138 residue tail is restored and is Sec-dependent by the addition of a leader sequence to the N-terminus of the protein. We also find that while there is no amphiphilic helix requirement for N-terminal translocation, there is a charge requirement that is needed within the tail; an arginine and lysine residue can inhibit or completely block translocation when introduced into the tail region. Intriguingly, the membrane potential is required for insertion of a 38 residue tail but not for a 23 residue tail.
Cao
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Department of Chemistry, Ohio State University, Columbus 43210.
Dalbey
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D000251:Adenosine Triphosphatases / Q000502:physiology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology; D001692:Biological Transport / Q000502:physiology; D002213:Capsid / Q000378:metabolism; D036022:Capsid Proteins; D004594:Electrophysiology; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D011487:Protein Conformation; D021382:Protein Sorting Signals / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D012697:Serine Endopeptidases; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D036022:Capsid Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D000069816:SEC Translocation Channels; C057841:SecY protein, E coli; C084332:major coat protein, Pseudomonas phage Pf3; D010450:Endopeptidases; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins