Chaperone SecB: conformational changes demonstrated by circular dichroism.

The chaperone SecB, which is involved in protein export in Escherichia coli, is shown by circular dichroism measurements to contain a high content of beta-pleated sheets. Prediction of the secondary structure of SecB is in good agreement with the observed content of beta-sheet. In accordance with the previous studies in which changes in conformation were assessed indirectly [Randall (1992), Science 257, 241-245], here we show that the conformation of SecB changes with the concentration of salt in the milieu and also when SecB interacts with a peptide ligand.