The Aspartic Proteinase Family of Three Phytophthora Species

Pepsin-like aspartic proteinases (APs) are produced in a wide variety of species and contain conserved motifs and landmark residues. APs fulfil critical roles in infectious organisms and their host cells. Phytophthora species are oomycete plant pathogens with major social and economic impact. Several of which have been sequenced. The genomes ofPhytophthora infestans, P. sojae and P. ramorum contain 11-12 genes encoding APs, resolved into 5 cladcs by phylogenetic analysis. Several subfamilies contain an unconventional architecture, as they either lack a signal peptide or a propart region. One of the Phytophthora APs is an unprecedented fusion protein with a putative G-protein coupled receptor as the C-terminal partner. The others appear to be related to welldocumented enzymes from other species including a vacuolar enzyme that is encoded in every fungal genome sequenced to date. The oomycetes also have enzymes similar to plasmepsin V, a membrane-bound AP in the malaria parasite Plasmodium falciparum, that cleaves effector proteins during their translocation into the host red blood cell. The translocation of Phytophthora effectors to host cells is topic of intense research in which APs might be involved