The protein Sf caspase-1 is the insect ortholog of the human effector caspases CASP3 (CPP32) and CASP7 (MCH3) in the species Spodoptera frugiperda (Fall armyworm).[1][2] It was identified as the target of the baculoviral caspase inhibitor protein P35, which it cleaves and by which it is inhibited.[1] Like other caspases, Sf caspase-1 is an aspartate-specific cysteine protease that is produced as an inactive proenzyme and becomes activated by autocatalytic cleavage.[1] The Sf caspase-1 proenzyme is cleaved after the amino acid residues Asp-28 and Asp-195, resulting in a smaller 12 kDa fragment and a larger 19 kDa fragment.[1][2] Just like with human caspases CASP3 or CASP7, the two cleavage fragments form heterodimers, which again form biologically active dimers-of-heterodimers consisting of two smaller and two larger fragments.[2] Some experiments also showed cleavage of Sf caspase-1 at the residue Asp-184, resulting in an 18 kDa instead of 19 kDa fragment, however this result is likely an in vitro artefact.[2] The insect immunophilin FKBP46 is a substrate of Sf caspase-1, which cleaves full length FKBP46 (~46 kDa) resulting in a ~25 kDa fragment.[1]

Sf caspase-1
Sf caspase-1 structure by Ni et al. 2006
Identifiers
OrganismSpodoptera frugiperda (Fall armyworm)
SymbolN/A
PDB2NN3
RefSeq (mRNA)U81510.1
RefSeq (Prot)AAC47442.1
UniProtP89116
Search for
StructuresSwiss-model
DomainsInterPro

References

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  1. ^ a b c d e Ahmad M, Srinivasula SM, Wang L, Litwack G, Fernandes-Alnemri T, Alnemri ES (January 1997). "Spodoptera frugiperda caspase-1, a novel insect death protease that cleaves the nuclear immunophilin FKBP46, is the target of the baculovirus antiapoptotic protein p35". The Journal of Biological Chemistry. 272 (3): 1421–4. doi:10.1074/jbc.272.3.1421. PMID 8999805.
  2. ^ a b c d Forsyth CM, Lemongello D, LaCount DJ, Friesen PD, Fisher AJ (February 2004). "Crystal structure of an invertebrate caspase". The Journal of Biological Chemistry. 279 (8): 7001–8. doi:10.1074/jbc.M312472200. PMID 14645217.