Highly selective binding of nascent polypeptides by an Escherichia coli chaperone protein in vivo.
Chaperone proteins bind to newly synthesized polypeptides and assist in various assembly reactions. The Escherichia coli chaperone protein SecB binds precursors of exported proteins and assists in export. In vitro, SecB can bind to many unfolded proteins. In this report, we demonstrate that SecB binding in vivo is highly selective; the major polypeptides that are bound by SecB are nascent precursors of the exported proteins maltose-binding protein (MBP), LamB, OmpF, and OmpA. These results support the hypothesis that the primary physiological function of SecB is to stimulate protein export. By interacting with nascent polypeptides, SecB probably stimulates their cotranslational association with the membrane-bound protein translocation apparatus.
Kumamoto
C A
CA
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
Francetić
O
O
D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism*
D001426:Bacterial Proteins; D011498:Protein Precursors; C057842:SecB protein, Bacteria