How the E. Coli Hsp70 Molecular Chaperone, DnaK, Binds a Client Protein

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Tilitsky, Joseph
Other Chemistry
thesis / dissertation description
Protein folding is essential for all cellular life. While some proteins are able to reach their folded state reliably using nothing but their amino acid sequence, a great number of essential proteins are unable to do so without the aid of molecular chaperones. One family of molecular chaperone, the Hsp70 family, is found in virtually all cell types and across all domains of life. Certain to the function of Hsp70s are how they bind their client proteins. Substantial effort has been expended to study how Hsp70s work on model peptides as a substrate mimic, but relatively little work has been performed using full-length protein substrates. This work examines how the E. coli Hsp70, DnaK, binds a full-length unfolded client protein, the pro-form of E. coli alkaline phosphatase, or proPhoA. I use a combination of biophysical techniques to under how DnaK binds proPhoA with regards to affinity, stoichiometry, and binding site selection. I find that DnaK binds each vii of the potential binding sites within proPhoA with roughly equal affinity. In addition, DnaK for a complex with proPhoA with a 1:1 stoichiometry and is selective for a single binding site on proPhoA.