Specific protein interaction of human Pag with Omi/HtrA2 and the activation of the protease activity of Omi/HtrA2.
The human PAG gene product (hPag), one member of the TSA/AhpC family, is overexpressed by oxidative stress, which causes apoptosis. To investigate the apoptotic signal transduction mediated by hPag, hPag-binding protein was screened using the yeast two-hybrid system. Omi/HtrA2 was identified as the hPag-binding protein. Omi/HtrA2, a potent proapoptotic factor, is released from the mitochondria into the cytoplasm as the mature form showing serine protease activity during apoptosis in response to oxidative stress. We found that hPag was able to interact with the mature form of Omi/HtrA2, not with the precursor form of Omi/HtrA2. The binding of Omi/HtrA2 to hPag was shown to involve the PDZ-binding domain in Omi/HtrA2. Also, the carboxyl-terminal domain of hPag was shown to be critical for the protein interaction. Using the yeast two-hybrid system and in vitro binding assay, the reduced form of hPag was able to interact with Omi/HtrA2. Interestingly, the protease activity given by the mature form of Omi/HtrA2 was significantly activated by the binding to hPag. Taken together, these results suggest that the specific protein interaction may participate as a molecular switch in modulating cell death in response to oxidative stress.
Hong
Seung-Keun
SK
Department of Biochemistry, Paichai University, 439-6 Doma-2-Dong Seo-Gu, Taejon 302-735, Korea.
Cha
Mee-Kyung
MK
Kim
Il-Han
IH
D048868:Adaptor Proteins, Signal Transducing; D004789:Enzyme Activation / Q000502:physiology; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins; D018384:Oxidative Stress / Q000502:physiology; D010447:Peptide Hydrolases / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; C498710:PAG1 protein, human; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D009195:Peroxidase; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; C000615914:HTRA2 protein, human; D000074923:High-Temperature Requirement A Serine Peptidase 2