title: The conformational dynamics of the mitochondrial Hsp70 chaperone.
abstract: 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.
authors.affiliation: Institute for Physiological Chemistry, LMU München, 81377 Munich, Germany.
authors.forename: Koyeli
authors.initials: K
authors.lastname: Mapa
authors.forename: Martin
authors.initials: M
authors.lastname: Sikor
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Kudryavtsev
authors.forename: Karin
authors.initials: K
authors.lastname: Waegemann
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kalinin
authors.forename: Claus A M
authors.initials: CA
authors.lastname: Seidel
authors.forename: Walter
authors.initials: W
authors.lastname: Neupert
authors.forename: Don C
authors.initials: DC
authors.lastname: Lamb
authors.forename: Dejana
authors.initials: D
authors.lastname: Mokranjac
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D050956:HSP40 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C087041:MDJ1 protein, S cerevisiae; D008565:Membrane Proteins; D018832:Molecular Chaperones; C101767:SSC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C063842:dnaK protein, E coli; D000252:Calcium-Transporting ATPases