title: Molecular basis for regulation of the heat shock transcription factor sigma32 by the DnaK and DnaJ chaperones.
abstract: Central to the transcriptional control of the Escherichia coli heat shock regulon is the stress-dependent inhibition of the sigma(32) subunit of RNA polymerase by reversible association with the DnaK chaperone, mediated by the DnaJ cochaperone. Here we identified two distinct sites in sigma(32) as binding sites for DnaK and DnaJ. DnaJ binding destabilizes a distant region of sigma(32) in close spatial vicinity of the DnaK-binding site, and DnaK destabilizes a region in the N-terminal domain, the primary target for the FtsH protease, which degrades sigma(32) in vivo. Our findings suggest a molecular mechanism for the DnaK- and DnaJ-mediated inactivation of sigma(32) as part of the heat shock response. They furthermore demonstrate that DnaK and DnaJ binding can induce conformational changes in a native protein substrate even at distant sites, a feature that we propose to be of general relevance for the action of Hsp70 chaperone systems.
authors.affiliation: Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Rodriguez
authors.forename: Florence
authors.initials: F
authors.lastname: Arsène-Ploetze
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rist
authors.forename: Stefan
authors.initials: S
authors.lastname: Rüdiger
authors.forename: Jens
authors.initials: J
authors.lastname: Schneider-Mergener
authors.forename: Matthias P
authors.initials: MP
authors.lastname: Mayer
authors.forename: Bernd
authors.initials: B
authors.lastname: Bukau
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002850:Chromatography, Gel; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins; D007700:Kinetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D012808:Sigma Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; D012808:Sigma Factor; C069774:heat-shock sigma factor 32; C063842:dnaK protein, E coli