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Conformational properties of bacterial DnaK and yeast mitochondrial Hsp70
Author(s) -
Moro Fernando,
FernándezSáiz Vanesa,
Slutsky Olga,
Azem Abdussalam,
Muga Arturo
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2005.04737.x
Subject(s) - escherichia coli , biology , hsp70 , yeast , chaperone (clinical) , peptide , saccharomyces cerevisiae , fusion protein , mitochondrion , biochemistry , protein structure , microbiology and biotechnology , cold shock domain , heat shock protein , peptide sequence , biophysics , n terminus , recombinant dna , rna , gene , medicine , pathology
Among the eukaryotic members of the Hsp70 family, mitochondrial Hsp70 shows the highest degree of sequence identity with bacterial DnaK. Although they share a functional mechanism and homologous co‐chaperones, they are highly specific and cannot be exchanged between Escherichia coli and yeast mitochondria. To provide a structural basis for this finding, we characterized both proteins, as well as two DnaK/mtHsp70 chimeras constructed by domain swapping, using biochemical and biophysical methods. Here, we show that DnaK and mtHsp70 display different conformational and biochemical properties. Replacing different regions of the DnaK peptide‐binding domain with those of mtHsp70 results in chimeric proteins that: (a) are not able to support growth of an E. coli DnaK deletion strain at stress temperatures (e.g. 42 °C); (b) show increased accessibility and decreased thermal stability of the peptide‐binding pocket; and (c) have reduced activation by bacterial, but not mitochondrial co‐chaperones, as compared with DnaK. Importantly, swapping the C‐terminal α‐helical subdomain promotes a conformational change in the chimeras to an mtHsp70‐like conformation. Thus, interaction with bacterial co‐chaperones correlates well with the conformation that natural and chimeric Hsp70s adopt in solution. Our results support the hypothesis that a specific protein structure might regulate the interaction of Hsp70s with particular components of the cellular machinery, such as Tim44, so that they perform specific functions.