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Interaction of SecB with intermediates along the folding pathway of maltose‐binding protein
Author(s) -
Diamond Deborah L.,
Strobel Sharon,
Chun SangYearn,
Randall Linda L.
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560040610
Subject(s) - maltose binding protein , chemistry , chaperone (clinical) , protein folding , folding (dsp implementation) , native state , biochemistry , maltose , biophysics , plasma protein binding , biology , enzyme , gene , fusion protein , medicine , engineering , pathology , electrical engineering , recombinant dna
SecB, a molecular chaperone involved in protein export in Escherichia coli , displays the remarkable ability to selectively bind many different polypeptide ligands whose only common feature is that of being nonnative. The selectivity is explained in part by a kinetic partitioning between the folding of a polypeptide and its association with SecB. SecB has no affinity for native, stably folded polypeptides but interacts tightly with polypeptides that are nonnative. In order to better understand the nature of the binding, we have examined the interaction of SecB with intermediates along the folding pathway of maltose‐binding protein. Taking advantage of forms of maltose‐binding protein that are altered in their folding properties, we show that the first intermediate in folding, represented by the collapsed state, binds to SecB, and that the polypeptide remains active as a ligand until it crosses the final energy barrier to attain the native state.