Ubiquitin protein ligase activity of the anti-apoptotic baculovirus protein Op-IAP3.
The baculovirus inhibitor of apoptosis protein (IAP) Op-IAP3 is required to prevent apoptosis during infection of insect cells by Orgyia pseudotsugata M nucleopolyhedrovirus (OpMNPV) and inhibits apoptosis when overexpressed in insect and mammalian cells. Although previous reports have demonstrated that the RING domain is important for the anti-apoptotic function of Op-IAP3, the function of this domain in Op-IAP3 has not been studied. Here, the ability of Op-IAP3 to function as an E3 ubiquitin protein ligase was examined. Op-IAP3 expressed in the insect cell line Spodoptera frugiperda (Sf21) was ubiquitinated, but only if the RING domain was intact. In addition, co-expression of Op-IAP3 and the pro-apoptotic Drosophila protein HID resulted in the ubiquitination of HID. Recombinant Op-IAP3 protein also promoted the ubiquitination of both itself and recombinant HID protein in vitro, and the ubiquitination of HID required both the RING and BIR2 of Op-IAP3. Thus, we conclude that Op-IAP3 is a functional E3 ubiquitin ligase, and the ability to ubiquitinate pro-apoptotic cellular proteins such as HID may play an important role in the anti-apoptotic function of Op-IAP3.
Molecular, Cellular, and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
Melissa C
MC
Green
Kristin P
KP
Monser
Rollie J
RJ
Clem
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D051034:Inhibitor of Apoptosis Proteins; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D017924:Nucleopolyhedroviruses / Q000201:enzymology* / Q000472:pathogenicity; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D018411:Spodoptera; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; C108880:HID protein, Drosophila; D051034:Inhibitor of Apoptosis Proteins; D009479:Neuropeptides; D011506:Proteins; D011994:Recombinant Proteins; D014764:Viral Proteins; D044767:Ubiquitin-Protein Ligases