Vacuolar proteases and autophagy in phytopathogenic fungi: A review.

Autophagy (macroautophagy) is a survival and virulence mechanism of different eukaryotic pathogens. Autophagosomes sequester cytosolic material and organelles, then fuse with or enter into the vacuole or lysosome (the lytic compartment of most fungal/plant cells and many animal cells, respectively). Subsequent degradation of cargoes delivered to the vacuole autophagy and endocytosis maintains cellular homeostasis and survival in conditions of stress, cellular differentiation, and development.

Heterologous expression and characterization of the aspartic endoprotease Pep4um from Ustilago maydis, a homolog of the human Chatepsin D, an important breast cancer therapeutic target.

The pep4um gene (um04926) of Ustilago maydis encodes a protein related to either vacuolar or lysosomal aspartic proteases. Bioinformatic analysis of the Pep4um protein revealed that it is a soluble protein with a signal peptide suggesting that it likely passes through the secretory pathway, and it has two probable self-activation sites, which are similar to those in Saccharomyces cerevisiae PrA. Moreover, the active site of the Pep4um has the two characteristic aspartic acid residues of aspartyl proteases.