Calorimetric analyses of the interaction between SecB and its ligands
Open Access
- 1 May 1998
- journal article
- research article
- Published by Wiley in Protein Science
- Vol. 7 (5), 1195-1200
- https://doi.org/10.1002/pro.5560070514
Abstract
SecB is a chaperone in Escherichia coli dedicated to export of proteins from the cytoplasm to the periplasm and outer membrane. It functions to bind and deliver precursors of exported proteins to the translocation apparatus before they fold into their native structures, thus maintaining them in a competent state for translocation across the membrane. The natural ligands of SecB are precursor proteins containing leader sequences. There are numerous reports in the literature indicating that SecB does not specifically recognize the leader peptides. However, two published investigations have concluded that the leader peptide is the recognition element (Watanabe M, Blobel G. 1989. Cell 58:685-705; Watanabe M, Blobel G. 1995. Proc Natl Acad Sci USA 92:10133-10136). In this work we use titration calorimetry to show that SecB binds two physiological ligands, which contain leader sequences, with no higher affinity than the same molecules lacking their leader sequences. Indeed, for one ligand the presence of the leader sequence reduces the affinity. Therefore, it can be concluded that the leader sequence provides no positive contribution to the binding energy.Keywords
This publication has 33 references indexed in Scilit:
- Determination of the binding frame of the chaperone SecB within the physiological ligand oligopeptide‐binding proteinProtein Science, 1997
- Electrospray mass spectrometric investigation of the chaperone SecBProtein Science, 1996
- Influence of the Signal Sequence and Chaperone SecB on the Interaction between Precursor Protein prePhoE and PhospholipidsJBIC Journal of Biological Inorganic Chemistry, 1996
- Diffusion-Limited Interaction between Unfolded Polypeptides and the Escherichia coli Chaperone SecBBiochemistry, 1995
- High selectivity with low specificity: how SecB has solved the paradox of chaperone bindingTrends in Biochemical Sciences, 1995
- Determination of the binding frame within a physiological ligand for the chaperone SecBProtein Science, 1994
- Biogenesis of outer membrane protein PhoE of Escherichia coli: Evidence for multiple SecB-binding sites in the mature portion of the PhoE proteinJournal of Molecular Biology, 1992
- SecB functions as a cytosolic signal recognition factor for protein export in E. coliCell, 1989
- The antifolding activity of SecB promotes the export of the E. coli maltose-binding proteinCell, 1988
- Synthesis of Exported Proteins by Membrane-Bound Polysomes from Escherichia coliEuropean Journal of Biochemistry, 1977