Interaction of SecB with soluble SecA.
The preprotein binding molecular chaperone SecB functions by preventing the premature folding of the preprotein in the cytosol, and targeting it to the peripheral subunit SecA of the translocase at the cytoplasmic membrane. The nature of the interaction of SecB with soluble SecA was studied by fluorescence anisotropy spectroscopy of Ru(bpy)2(dcbpy)-labeled SecA in the presence of increasing concentrations of SecB. A more than 50-fold difference in affinity for the cytosolic SecA compared to translocase associated SecA seems to prevent unproductive binding of SecB to the cytosolic SecA and stresses its targeting function.
den Blaauwen
T
T
Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
Terpetschnig
E
E
Lakowicz
J R
JR
Driessen
A J
AJ
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005454:Fluorescence Polarization; D008027:Light; D026901:Membrane Transport Proteins; D011485:Protein Binding; D017510:Protein Folding; D012413:Rubidium; D000069816:SEC Translocation Channels; D012542:Scattering, Radiation; D000081416:SecA Proteins
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C057842:SecB protein, Bacteria; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins; D012413:Rubidium