Co-translational folding of caspase-activated DNase with Hsp70, Hsp40, and inhibitor of caspase-activated DNase.
CAD (caspase-activated DNase) that causes chromosomal DNA fragmentation during apoptosis exists as a complex with ICAD (inhibitor of CAD) in proliferating cells. Here, we report that denatured CAD is functionally refolded with Hsc70-Hsp40 and ICAD. Hsc70-Hsp40 suppresses the aggregation of the denatured CAD, but cannot restore its enzymatic activity. In contrast, ICAD could not suppress the aggregation of CAD, but supported the CAD's renaturation with Hsc70-Hsp40, indicating that ICAD recognizes the quasi-native folding state of CAD that is conferred by Hsc70-Hsp40. Using an in vitro translation system, we then showed that during CAD translation, Hsc70-Hsp40 as well as ICAD bind to the nascent CAD polypeptide, while on ribosomes. These results indicate that ICAD together with Hsc70-Hsp40 assists the folding of CAD during its synthesis, and that the CAD*ICAD heterodimer is formed co-translationally.
Sakahira
Hideki
H
Department of Genetics, Osaka University Medical School, and Core Research for Evolutional Science and Technology, Japan.
Nagata
Shigekazu
S
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001665:Binding Sites; D003001:Cloning, Molecular; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D014176:Protein Biosynthesis; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation; D011506:Proteins / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012156:Reticulocytes / Q000201:enzymology
D051017:Apoptosis Regulatory Proteins; D000939:Epitopes; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D010446:Peptide Fragments; D011506:Proteins; D011994:Recombinant Proteins; C109664:caspase-activated DNase inhibitor; D000255:Adenosine Triphosphate; D003851:Deoxyribonucleases; C109663:caspase-activated deoxyribonuclease