cDNA cloning of a novel cysteine protease of Plasmodium falciparum

The cDNA for a novel Plasmodium cysteine protease (falcipain-2) has been is olated from a Plasmodium falciparum cDNA library. A 602 bp fragment was amp lified from P. falciparum by PCR using degenerate oligonucleotide primers. The primers were designed based upon the amino acids flanking the active si te cysteine and asparagine residues that are conserved in the eukaryotic cy steine proteases. This fragment was used to screen a P. falciparum cDNA lib rary and isolated a 2.1 kb clone that encoded a novel cysteine protease. Th e sequence of the 2.1 kb clone predicted a 56 kDa protein containing a typi cal signal sequence, a prosequence and a 24.7 kDa mature protease with 37% identity to falcipain-1, a hemoglobin-degrading cysteine protease of P. fal ciparum. Northern blot analysis detected a 2.1 kb message in trophozoites. Taken together, we have isolated a novel cysteine protease of P. falciparum , which may play an important role at the late stages of the erythrocytic c ycle of the parasite. (C) 2000 Elsevier Science B.V. All rights reserved.