The role of Aspartyl aminopeptidase (Ape4) in Cryptococcus neoformans virulence and authophagy

Author(s)

Gontijo, Fabiano de Assis ; de Melo, Amanda Teixeira ; Pascon, Renata C. ; Fernandes, Larissa ; Paes, Hugo Costa ; Alspaugh, J. Andrew ; Vallim, Marcelo A.

• Document type: Journal article
• Source: PLoS One; v. 12, n. 5 MAY 25 2017.
• Web of Science Citations: 4

Abstract

In order to survive and cause disease, microbial pathogens must be able to proliferate at the temperature of their infected host. We identified novel microbial features associated with thermotolerance in the opportunistic fungal pathogen Cryptococcus neoformans using a random insertional mutagenesis strategy, screening for mutants with defective growth at 37 degrees C. Among several thermosensitive mutants, we identified one bearing a disruption in a gene predicted to encode the Ape4 aspartyl aminopeptidase protein. Ape4 metalloproteases in other fungi, including Saccharomyces cerevisiae, are activated by nitrogen starvation, and they are required for autophagy and the cytoplasm-to-vacuole targeting (Cvt) pathway. However, none have been previously associated with altered growth at elevated temperatures. We demonstrated that the C. neoformans ape4 mutant does not grow at 37 degrees C, and it also has defects in the expression of important virulence factors such as phospholipase production and capsule formation. C. neoformans Ape4 activity was required for this facultative intracellular pathogen to survive within macrophages, as well as for virulence in an animal model of cryptococcal infection. Similar to S. cerevisiae Ape4, the C. neoformans GFP-Ape4 fusion protein co-localized with intracytoplasmic vesicles during nitrogen depletion. APE4 expression was also induced by the combination of nutrient and thermal stress. Together these results suggest that autophagy is an important cellular process for this microbial pathogen to survive within the environment of the infected host. (AU)

• FAPESP's process: 16/14542-8 - Genetic characterization of the regulatory elements of the biosynthesis and uptake of amino acids and their role in virulence of Cryptococcus neoformans.
• Grantee: Renata Castiglioni Pascon
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/04400-9 - The role of autophagy in Cryptococcus neorformas high temperature (37°C) growth and virulence
• Grantee: Marcelo Afonso Vallim
• Support Opportunities: Regular Research Grants