Redox mechanism for the chaperone activity of heat shock proteins HSPs 60, 70 and 90 as suggested by hydrophobic cluster analysis: hypothesis.
We have recently shown that the N-terminal ATPase fragment of hsp70 (1-375, composed of domains I and II) as well as the subsequent domain III (376-520) may share three-dimensional similarities with hsp60. In this study, we propose that domain III, common to the hsp60s and hsp70s is also found in the hsp90s and adopts a beta-alpha-beta Rossmann-folded structure which is encountered in the NAD-binding domain of dehydrogenases. Consequently, with the help of the domain IV (in hsp70s and hsp90s) or of hsp10/GroES (in hsp60s) and possibly that of auxilliary partners, the hsp molecules could act as "unfoldases" or "reset systems" by disrupting secondary structures through redox reactions on the main polypeptidic chain with which they interact. The models built on this hypothesis may open up a new way for understanding the chaperone functions within the folding/unfolding processes.
Callebaut
I
I
Département des Macromolécules Biologiques, CNRS URA09, Universités Paris VI-Paris VII, France.
Catelli
M G
MG
Portetelle
D
D
Meng
X
X
Cadepond
F
F
Burny
A
A
Baulieu
E E
EE
Mornon
J P
JP
D018834:Chaperonin 60 / Q000378:metabolism* / Q000648:ultrastructure; D016000:Cluster Analysis; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism* / Q000648:ultrastructure; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism* / Q000648:ultrastructure; D066298:In Vitro Techniques; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011485:Protein Binding; D017510:Protein Folding
D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins