Taxonomic distribution of proteins containing BIR domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing BIR domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

An apoptosis-inhibiting gene from a nuclear polyhedrosis virus encoding a polypeptide with Cys/His sequence motifs.

Birnbaum MJ, Clem RJ, Miller LK
J Virol. 1994; 68: 2521-8

Two different baculovirus genes are known to be able to block apoptosis triggered upon infection of Spodoptera frugiperda cells with p35 mutants of the insect baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV):p35 (P35-encoding gene) of AcMNPV (R. J. Clem, M. Fechheimer, and L. K. Miller, Science 254:1388-1390, 1991) and iap (inhibitor of apoptosis gene) of Cydia pomonella granulosis virus (CpGV) (N. E. Crook, R. J. Clem, and L. K. Miller, J. Virol. 67:2168-2174, 1993). Using a genetic complementation assay to identify additional genes which inhibit apoptosis during infection with a p35 mutant, we have isolated a gene from Orgyia pseudotsugata NPV (OpMNPV) that was able to functionally substitute for AcMNPV p35. The nucleotide sequence of this gene, Op-iap, predicted a 30-kDa polypeptide product with approximately 58% amino acid sequence identity to the product of CpGV iap, Cp-IAP. Like Cp-IAP, the predicted product of Op-iap has a carboxy-terminal C3HC4 zinc finger-like motif. In addition, a pair of additional cysteine/histidine motifs were found in the N-terminal regions of both polypeptide sequences. Recombinant p35 mutant viruses carrying either Op-iap or Cp-iap appeared to have a normal phenotype in S. frugiperda cells. Thus, Cp-IAP and Op-IAP appear to be functionally analogous to P35 but are likely to block apoptosis by a different mechanism which may involve direct interaction with DNA.

An apoptosis-inhibiting baculovirus gene with a zinc finger-like motif.

Crook NE, Clem RJ, Miller LK
J Virol. 1993; 67: 2168-74

Spodoptera frugiperda SF-21 cells infected with Autographa californica nuclear polyhedrosis virus mutants which lack a functional p35 gene undergo apoptosis, a type of programmed cell death. To identify p35-homologous genes in other baculoviruses, A. californica nuclear polyhedrosis virus DNA containing a deletion in p35 was cotransfected into SF-21 cells along with genomic DNAs from other baculoviruses. One of the viral DNAs which were able to rescue wild-type infection was from Cydia pomonella granulosis virus (CpGV). The CpGV gene responsible for the effect was mapped to a 1.6-kb SalI-SstI subclone of the SalI B fragment of CpGV. The sequence of the SalI-SstI subclone revealed an open reading frame capable of encoding a polypeptide of 31 kDa which was sufficient to rescue wild-type infection; this gene was thus called iap (inhibitor of apoptosis). The predicted sequence of the IAP polypeptide exhibited no significant homology to P35 but contained a zinc finger-like motif which is also found in other genes with the potential to regulate apoptosis, including several mammalian proto-oncogenes and two insect genes involved in embryonic development. In the context of the viral genome, both iap and p35 were able to block apoptosis induced by actinomycin D, indicating that these genes act by blocking cellular apoptosis rather than by preventing viral stimulation of apoptosis. Several independent recombinant viruses derived from cotransfections with either the entire CpGV genome or the 1.6-kb subclone were characterized.