Thermal adaptation of heat shock proteins.
Heat shock proteins (Hsps) are molecular chaperones that oppose stress-induced denaturation of other proteins. Hsps are present in all organisms. Apart from assisting in the efficient folding of newly synthesized proteins they maintain pre-existing proteins in a stable conformation, preventing their aggregation, under stress conditions. The latter role, essential for thermal adaptation, requires that the chaperone system change from a folding to a storing function at heat shock temperatures. The temperature at which this change occurs depends on the presence of a thermosensor in at least one of the components of the chaperone systems. In this review, we focus on the bacterial GroE and DnaK systems, describe their temperature-sensitive protein components, and the location of the thermosensor within the structure of these components. While the thermosensor of the GroE system is located at the inter-ring interface of GroEL, that of the DnaK system occurs in its co-chaperone GrpE. Analysis of these examples demonstrates the amazing mechanistic diversity of thermal stress adaptation and of functional convergence of structurally unrelated proteins.
Muga
A
A
Unidad de Biofísica and Departamento de Bioquímica y Biología Molecular, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Bilbao, Spain. arturo.muga@ehu.es
Moro
F
F
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018835:Chaperonin 10 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D006358:Hot Temperature; D006801:Humans; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation
D001426:Bacterial Proteins; D018835:Chaperonin 10; C068113:GrpE protein, Bacteria; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones