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Deducing the Origin of Hsp70 Binding Selectivity by Structural Study
Author(s) -
Jansen Rachel M.,
Clerico Eugenia M.,
Ozden Can,
Gierasch Lila M.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.04504
Subject(s) - chaperone (clinical) , binding site , protein folding , peptide , chemistry , hsp70 , plasma protein binding , biochemistry , protein structure , biophysics , computational biology , heat shock protein , biology , gene , medicine , pathology
Hsp70s are a family of molecular chaperone proteins that aid in the folding of other proteins under physiological and stress conditions. Chaperones prevent protein misfolding and aggregation, characteristic of many neurodegenerative diseases. Hsp70s perform their chaperoning functions through interactions between their substrate binding domain (SBD) and short hydrophobic sequences of their non‐native protein clients that are exposed to the solvent. The details of the interaction between the chaperone and diverse sequences remain poorly understood. Much of the work on the interaction between Hsp70s and client proteins has been done using DnaK, the E.coli Hsp70 and short peptides as surrogates for the client protein. In 1996, the 3D structure of the SBD of DnaK bound to one model peptide was determined using x‐ray crystallography (Zhu et al., 1996), and more recently, the forward and reverse binding between the SBD and a few small peptides has been observed (Zahn el al., 2013). Therefore, it is known that the SBD can accommodate numerous sequences but is nonetheless selective in which sequences it binds. This project aims to understand this “promiscuous selectivity” through analyzing the atomic resolution structures of SBD bound to various peptides. To begin dissecting the selective promiscuity of SBD binding to various sequences we are using proPhoA, an endogenous substrate of DnaK, that has been shown to have five DnaK binding sites. We have determined structures of the SBD of DnaK bound to three of the five binding sites in proPhoA using x‐ray crystallography. These structures reveal a variety of binding modes despite a uniformity of the backbone conformation for the bound peptides. Using this detailed atomic resolution information, we are dissecting how the peptides bind in the SBD and if the SBD remodels to accommodate these unique but specific sequences. This information is shedding light on the basis of Hsp70/substrate recognition. Support or Funding Information 1. NIH R35 GM118161 MIRA Grant "Protein folding in the Cell: Challenges and Coping Mechanisms" 6/1/16 – 5/31/2021 2. University of Massachusetts ‐ Amherst ‐ Biochemistry and Molecular Biology Department