Document Detail


Host insect inhibitor-of-apoptosis SfIAP functionally replaces baculovirus IAP but is differentially regulated by Its N-terminal leader.
MedLine Citation:
PMID:  20739517     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The inhibitor-of-apoptosis (IAP) proteins encoded by baculoviruses bear a striking resemblance to the cellular IAP homologs of their invertebrate hosts. By virtue of the acquired selective advantage of blocking virus-induced apoptosis, baculoviruses may have captured cellular IAP genes that subsequently evolved for virus-specific objectives. To compare viral and host IAPs, we defined antiapoptotic properties of SfIAP, the principal cellular IAP of the lepidopteran host Spodoptera frugiperda. We report here that SfIAP prevented virus-induced apoptosis as well as viral Op-IAP3 (which is encoded by the Orgyia pseudotsugata nucleopolyhedrovirus) when overexpressed from the baculovirus genome. Like Op-IAP3, SfIAP blocked apoptosis at a step prior to caspase activation. Both of the baculovirus IAP repeats (BIRs) were required for SfIAP function. Moreover, deletion of the C-terminal RING motif generated a loss-of-function SfIAP that interacted and dominantly interfered with wild-type SfIAP. Like Op-IAP3, wild-type SfIAP formed intracellular homodimers, suggesting that oligomerization is a functional requirement for both cellular and viral IAPs. SfIAP possesses a ∼100-residue N-terminal leader domain, which is absent among all viral IAPs. Remarkably, deletion of the leader yielded a fully functional SfIAP with dramatically increased protein stability. Thus, the SfIAP leader contains an instability motif that may confer regulatory options for cellular IAPs that baculovirus IAPs have evolved to bypass for maximal stability and antiapoptotic potency. Our findings that SfIAP and viral IAPs have common motifs, share multiple biochemical properties including oligomerization, and act at the same step to block apoptosis support the hypothesis that baculoviral IAPs were derived by acquisition of host insect IAPs.
Authors:
Rebecca J Cerio; Rianna Vandergaast; Paul D Friesen
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-08-25
Journal Detail:
Title:  Journal of virology     Volume:  84     ISSN:  1098-5514     ISO Abbreviation:  J. Virol.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-08     Completed Date:  2010-11-04     Revised Date:  2011-07-28    
Medline Journal Info:
Nlm Unique ID:  0113724     Medline TA:  J Virol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11448-60     Citation Subset:  IM    
Affiliation:
Institute for Molecular Virology, Department of Biochemistry, Graduate School and College of Agricultural and Life Sciences, University of Wisconsin-Madison, 1525 Linden Dr., Madison, WI 53706-1596, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Apoptosis
Baculoviridae / genetics*
Genome, Viral
Host-Pathogen Interactions / genetics*
Inhibitor of Apoptosis Proteins / genetics*
Protein Stability
Spodoptera / genetics*,  microbiology
Grant Support
ID/Acronym/Agency:
AI25557/AI/NIAID NIH HHS; AI40482/AI/NIAID NIH HHS; T32 GM07215/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Inhibitor of Apoptosis Proteins
Comments/Corrections

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