Low Concentrations of Hydrogen Peroxide or Nitrite Induced of Paracoccidioides brasiliensis Cell Proliferation in a Ras-Dependent Manner

Author(s)

Coronel Janu Haniu, Ana Eliza ^[1] ; Maricato, Juliana Terzi ^[1] ; Moraes Mathias, Pedro Paulo ^[2] ; Castilho, Daniele Goncalves ^[1] ; Miguel, Rodrigo Bernardi ^[2] ; Monteiro, Hugo Pequeno ^[2] ; Puccia, Rosana ^[1] ; Batista, Wagner Luiz ^{[3, 1]}

Affiliation

^[1] Univ Fed Sao Paulo, Dept Microbiol Imunol & Parasitol, Sao Paulo - Brazil

^[2] Univ Fed Sao Paulo, Ctr Terapia Celular & Mol CTCMol, Dept Bioquim Biol Mol, Sao Paulo - Brazil

^[3] Univ Fed Sao Paulo, Dept Ciencias Biol, Sao Paulo - Brazil

• Document type: Journal article
• Source: PLoS One; v. 8, n. 7 JUL 29 2013.
• Web of Science Citations: 11

Abstract

Paracoccidioides brasiliensis, a causative agent of paracoccidioidomycosis (PCM), should be able to adapt to dramatic environmental changes inside the infected host after inhalation of air-borne conidia and transition to pathogenic yeasts. Proteins with antioxidant functions may protect fungal cells against reactive oxygen (ROS) and nitrogen (RNS) species generated by phagocytic cells, thus acting as potential virulence factors. Ras GTPases are involved in stress responses, cell morphology, and differentiation in a range of organisms. Ras, in its activated form, interacts with effector proteins and can initiate a kinase cascade. In lower eukaryotes, Byr2 kinase represents a Ras target. The present study investigated the role of Ras in P. brasiliensis after in vitro stimulus with ROS or RNS. We have demonstrated that low concentrations of H2O2 (0.1 mM) or NO2 (0.1-0.25 mu M) stimulated P. brasiliensis yeast cell proliferation and that was not observed when yeast cells were pre-incubated with farnesyltransferase inhibitor. We constructed an expression plasmid containing the Byr2 Ras-binding domain (RBD) fused with GST (RBD-Byr2-GST) to detect the Ras active form. After stimulation with low concentrations of H2O2 or NO2, the Ras active form was observed in fungal extracts. Besides, NO2 induced a rapid increase in S-nitrosylated Ras levels. This alternative posttranslational modification of Ras, probably in residue Cys123, would lead to an exchange of GDP for GTP and consequent GTPase activation in P. brasiliensis. In conclusion, low concentrations of H2O2 or NO2 stimulated P. brasiliensis proliferation through Ras activation. (AU)

• FAPESP's process: 11/14392-2 - Evaluation of the involvement of Ras GTPase from Paracoccidioides brasiliensis in thermo-dimorphism and during oxidative and nitrosative stress
• Grantee: Wagner Luiz Batista
• Support Opportunities: Regular Research Grants