The Conformational Dynamics of the Mitochondrial Hsp70 Chaperone

• Published in: Molecular cell Vol. 38; no. 1; pp. 89 - 100
• Main Authors: Mapa, Koyeli, Sikor, Martin, Kudryavtsev, Volodymyr, Waegemann, Karin, Kalinin, Stanislav, Seidel, Claus A.M., Neupert, Walter, Lamb, Don C., Mokranjac, Dejana
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 09.04.2010
• Subjects: Adenosine Diphosphate - chemistry; Adenosine Diphosphate - metabolism; Adenosine Triphosphate - chemistry; Adenosine Triphosphate - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Calcium-Transporting ATPases - chemistry; Calcium-Transporting ATPases - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Fluorescence Resonance Energy Transfer; HSP40 Heat-Shock Proteins - chemistry; HSP40 Heat-Shock Proteins - metabolism; HSP70 Heat-Shock Proteins - chemistry; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Humans; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Mitochondria - metabolism; Models, Molecular; Molecular Chaperones - chemistry; Molecular Chaperones - metabolism; Protein Conformation; Protein Folding; PROTEINS; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; PROTEINS
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2010.03.010

Heat shock proteins 70 (Hsp70) represent a ubiquitous and conserved family of molecular chaperones involved in a plethora of cellular processes. The dynamics of their ATP hydrolysis-driven and cochaperone-regulated conformational cycle are poorly understood. We used fluorescence spectroscopy to analyze, in real time and at single-molecule resolution, the effects of nucleotides and cochaperones on the conformation of Ssc1, a mitochondrial member of the family. We report that the conformation of its ADP state is unexpectedly heterogeneous, in contrast to a uniform ATP state. Substrates are actively involved in determining the conformation of Ssc1. The J protein Mdj1 does not interact transiently with the chaperone, as generally believed, but rather is released slowly upon ATP hydrolysis. Analysis of the major bacterial Hsp70 revealed important differences between highly homologous members of the family, possibly explaining tuning of Hsp70 chaperones to meet specific functions in different organisms and cellular compartments. ► ADP state of mitochondrial Hsp70 is heterogeneous, whereas its ATP state is uniform ► Substrates actively influence the conformation of mtHsp70 ► J protein Mdj1 remains bound to mtHsp70 for minutes after ATP hydrolysis ► Conformational changes upon ATP hydrolysis are conveyed differently in DnaK