Figure 4

Protease inhibitors in Saprolegnia parasitica. (A) Sequence alignment of Sp_001_01027 predicted amino acid sequence with representative Kazal family inhibitor domains. Protein names correspond to protease inhibitors of Saprolegnia parasitica Sp_001_01027, Phytophthora infestans EPI1 (EPI1a-b, AY586273) and EPI10 (EPI10a-c, AY586282), the crayfish Pacifastacus leniusculus (PAPI-1a-d, CAA56043), and the apicomplexan Toxoplasma gondii (TgPI-1a-d, AF121778). The conserved cysteine residues that define the Kazal family protease inhibitor domain are marked with asterisks. The putative disulfide linkages formed by cysteine residues within the predicted Kazal domains are shown. The position of the predicted P1 residues is shown by an arrow. (B) Sequence alignment of Saprolegnia parasitica Sp_001_01374 (N-terminal fragment of the mature protein), chicken egg white cystatin (CHKCYS, P01038, mature protein), rice oryzacystatin-I (Oryzacystatin-I, P09229), human cystatin A (CYTA_human, P01040) and cystatin B (CYTB_human, P04080). The proposed active-site residues in cystatins, forming the N-terminal trunk (NT) and first binding loop (L1), are indicated.