Characterization of the aggregation-prevention activity of p97/valosin-containing protein.
The 97 kDa valosin-containing protein (VCP) belongs to a highly conserved AAA (ATPases associated with a variety of activities) family and contains two ATPase domains, D1 and D2. VCP participates in numerous cellular activities, such as membrane fusion, postmitotic Golgi reassembly, endoplasmic reticulum-associated degradation, ubiquitin-proteasome-mediated proteolysis, and many others. In performing these activities, VCP presumably acts as a molecular chaperone that prevents protein aggregation and modifies protein conformation. In this study, we characterized the aggregation-prevention activity of VCP and identified the structural requirement for this activity. We used multiple methods to treat aggregation-prone luciferase (Luc) and showed that VCP prevents the aggregation of Luc in vitro. These results are in agreement; in vivo RNA interference analyses showed that a reduction of VCP level results in more aggregation of Luc in cells. Structural and functional analyses further demonstrated that the D1 domain of VCP is sufficient to mediate the aggregation-prevention activity, which does not require ATP binding, ATP hydrolysis, or a hexameric structure of VCP. Together, these results indicate that (1) VCP prevents protein aggregation in vitro and in vivo, (2) this aggregation-prevention activity is mediated mainly through the D1 domain of VCP, and (3) this activity does not require ATPase activity or a hexameric structure of VCP.
Song
Changcheng
C
Laboratory of Cancer Prevention, NCI-Frederick, Frederick, Maryland 21702, USA. songc@ncifcrf.gov
Wang
Qing
Q
Li
Chou-Chi H
CC
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011489:Protein Denaturation; D013696:Temperature; D000074405:Valosin Containing Protein
D018797:Cell Cycle Proteins; D000251:Adenosine Triphosphatases; C000614178:VCP protein, human; D000074405:Valosin Containing Protein