The chaperone activity of protein disulfide isomerase is affected by cyclophilin B and cyclosporin A in vitro.
To elucidate the function of protein disulfide isomerase (PDI), we screened for PDI-binding proteins in a bovine liver extract using affinity column chromatography. One of the binding proteins was identified by SDS-PAGE and N-terminal amino acid sequence analysis to be cyclophilin B (Cyp B). Use of the BIACORE system revealed that purified bovine Cyp B bound specifically to bovine PDI with a K(D) value of 1.19 x 10(-5) M. Interestingly, the binding affinity between PDI and Cyp B was strengthened by preincubation of the Cyp B with cyclosporin A (CsA), yielding a K(D) value of 3.67 x 10(-6) M. Although the interaction between PDI and Cyp B affected neither the isomerase activity of PDI nor the peptidyl-prolyl cis-trans isomerase activity of Cyp B, Cyp B increased the chaperone activity of PDI. However, the complex of Cyp B and CsA completely inhibited the chaperone activity of PDI. Thus, PDI and Cyp B appear to cooperate with each other to regulate the functional expression of proteins in vivo.
Horibe
Tomohisa
T
Department of Bioscience & Technology, Faculty of Science & Engineering, Ritsumeikan University, Noji-higashi, Kusatsu, Shiga 525-8577, Japan.
Yosho
Chieko
C
Okada
Satoshi
S
Tsukamoto
Masami
M
Nagai
Hiroaki
H
Hagiwara
Yasunari
Y
Tujimoto
Yoshiyuki
Y
Kikuchi
Masakazu
M
D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D021983:Cyclophilins / Q000494:pharmacology*; D016572:Cyclosporine / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism*; D019696:Peptidylprolyl Isomerase; D011485:Protein Binding; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*
D018832:Molecular Chaperones; C081786:cyclophilin B; D016572:Cyclosporine; D021983:Cyclophilins; D019696:Peptidylprolyl Isomerase; D019704:Protein Disulfide-Isomerases