Alternate recruitment of signal recognition particle and trigger factor to the signal sequence of a growing nascent polypeptide.
Different from cytoplasmic membrane proteins, presecretory proteins of bacteria usually do not require the signal recognition particle for targeting to the Sec translocon. Nevertheless signal sequences of presecretory proteins have been found in close proximity to signal recognition particle immediately after they have emerged from the ribosome. We show here that at the ribosome, the molecular environment of a signal sequence depends on the nature of downstream sequence elements that can cause an alternate recruitment of signal recognition particle and the ribosome-associated chaperone Trigger factor to a growing nascent chain. While signal recognition particle and Trigger factor might remain bound to the same ribosome, both ligands are clearly able to displace each other from a nascent chain. The data also imply that a signal sequence owes its molecular environment to the fact that it remains closely apposed to the ribosomal exit site during growth of a nascent secretory protein.
Eisner
Gottfried
G
Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
Moser
Michael
M
Schäfer
Ute
U
Beck
Konstanze
K
Müller
Matthias
M
D000251:Adenosine Triphosphatases / Q000737:chemistry; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D026901:Membrane Transport Proteins / Q000737:chemistry; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry*; D019696:Peptidylprolyl Isomerase / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D018271:Signal Recognition Particle / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; D008024:Ligands; D026901:Membrane Transport Proteins; D010455:Peptides; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle; C078167:OMPA outer membrane proteins; D000251:Adenosine Triphosphatases; C403324:trigger factor, E coli; D019696:Peptidylprolyl Isomerase; D000081416:SecA Proteins