Sf caspase-1

Sf caspase-1
Sf caspase-1 structure by Ni et al. 2006
Identifiers
Organism	Spodoptera frugiperda (Fall armyworm)
Symbol	N/A
PDB	2NN3
RefSeq (mRNA)	U81510.1
RefSeq (Prot)	AAC47442.1
UniProt	P89116

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 a 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]

References

1. Ahmad, Manzoor; Srinivasula, S. M.; Wang, L; Litwack, G; Fernandes-Alnemri, T; Alnemri, E. S. (17 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". Journal of Biological Chemistry. 272 (3): 1421–4. doi:10.1074/jbc.272.3.1421. PMID 8999805.
2. Forsyth, Charles M.; Lemongello, Donna; LaCount, Douglas J.; Friesen, Paul D.; Fisher, Andrew J. (20 February 2004). "Crystal Structure of an Invertebrate Caspase". Journal of Biological Chemistry. 279 (8): 7001–7008. doi:10.1074/jbc.M312472200. PMID 14645217.