TY - JOUR
T1 - HSP40 binding is the first step in the HSP90 chaperoning pathway for the progesterone receptor
AU - Patricia Hernández, M.
AU - Chadli, Ahmed
AU - Toft, David O.
PY - 2002/4/5
Y1 - 2002/4/5
N2 - The progesterone receptor (PR) can be isolated in its native conformation able to bind hormone, yet its ligand-binding domain rapidly loses its activity at elevated temperature. However, an in vitro chaperoning system consisting of five proteins (HSP40, HSP70, HOP, HSP90, and p23) with ATP is capable of restoring this function. The first step of this chaperoning mechanism is usually thought to be the binding of HSP70 to PR. Our findings here show that the binding of HSP40 to PR is, instead, the first step. HSP40 binding occurred rapidly and was not dependent on ATP or other proteins. The stoichiometry of HSP40 to native PR in these complexes was ∼1:1. HSP40 bound specifically and with a high affinity to native PR (Kd = 77 nM). The binding of HSP40 to PR was sustained and did not interact in the highly dynamic fashion that has been observed previously for HSP90 in this system. The HSP40·PR complex could be isolated as a functional unit that could, after the addition of the other chaperones, progress to a PR complex capable of hormone binding. These results indicate that HSP40 initiates the entry of PR into the HSP90 pathway.
AB - The progesterone receptor (PR) can be isolated in its native conformation able to bind hormone, yet its ligand-binding domain rapidly loses its activity at elevated temperature. However, an in vitro chaperoning system consisting of five proteins (HSP40, HSP70, HOP, HSP90, and p23) with ATP is capable of restoring this function. The first step of this chaperoning mechanism is usually thought to be the binding of HSP70 to PR. Our findings here show that the binding of HSP40 to PR is, instead, the first step. HSP40 binding occurred rapidly and was not dependent on ATP or other proteins. The stoichiometry of HSP40 to native PR in these complexes was ∼1:1. HSP40 bound specifically and with a high affinity to native PR (Kd = 77 nM). The binding of HSP40 to PR was sustained and did not interact in the highly dynamic fashion that has been observed previously for HSP90 in this system. The HSP40·PR complex could be isolated as a functional unit that could, after the addition of the other chaperones, progress to a PR complex capable of hormone binding. These results indicate that HSP40 initiates the entry of PR into the HSP90 pathway.
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U2 - 10.1074/jbc.M111445200
DO - 10.1074/jbc.M111445200
M3 - Article
C2 - 11809754
AN - SCOPUS:0037023732
SN - 0021-9258
VL - 277
SP - 11873
EP - 11881
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 14
ER -