Redox proteomics changes in the fungal pathogen Trichosporon asahii on arsenic exposure: identification of protein responses to metal-induced oxidative stress in an environmentally-sampled isolate

PLoS One. 2014 Jul 25;9(7):e102340. doi: 10.1371/journal.pone.0102340. eCollection 2014.

Abstract

Trichosporon asahii is a yeast pathogen implicated in opportunistic infections. Cultures of an isolate collected from industrial wastewater were exposed for 2 days to 100 mg/L sodium arsenite (NaAsO2) and cadmium (CdCl2). Both metals reduced glutathione transferase (GST) activity but had no effect on superoxide dismutase or catalase. NaAsO2 exposure increased glutathione reductase activity while CdCl2 had no effect. Protein thiols were labeled with 5-iodoacetamido fluorescein followed by one dimensional electrophoresis which revealed extensive protein thiol oxidation in response to CdCl2 treatment but thiol reduction in response to NaAsO2. Two dimensional electrophoresis analyses showed that the intensity of some protein spots was enhanced on treatment as judged by SameSpots image analysis software. In addition, some spots showed decreased IAF fluorescence suggesting thiol oxidation. Selected spots were excised and tryptic digested for identification by MALDI-TOF/TOF MS. Twenty unique T. asahii proteins were identified of which the following proteins were up-regulated in response to NaAsO2: 3-isopropylmalate dehydrogenase, phospholipase B, alanine-glyoxylate aminotransferase, ATP synthase alpha chain, 20S proteasome beta-type subunit Pre3p and the hypothetical proteins A1Q1_08001, A1Q2_03020, A1Q1_06950, A1Q1_06913. In addition, the following showed decreased thiol-associated fluorescence consistent with thiol oxidation; aconitase; aldehyde reductase I; phosphoglycerate kinase; translation elongation factor 2; heat shock protein 70 and hypothetical protein A1Q2_04745. Some proteins showed both increase in abundance coupled with decrease in IAF fluorescence; 3-hydroxyisobutyryl-CoA hydrolase; homoserine dehydrogenase Hom6 and hypothetical proteins A1Q2_03020 and A1Q1_00754. Targets implicated in redox response included 10 unique metabolic enzymes, heat shock proteins, a component of the 20S proteasome and translation elongation factor 2. These data suggest extensive proteomic alterations in response to metal-induced oxidative stress in T. asahii. Amino acid metabolism, protein folding and degradation are principally affected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arsenites / toxicity
  • Cadmium / toxicity
  • Electrophoresis, Gel, Two-Dimensional
  • Gene Expression Regulation, Fungal / drug effects*
  • Glutathione
  • Glutathione Transferase / biosynthesis
  • Glutathione Transferase / metabolism
  • Oxidation-Reduction*
  • Oxidative Stress / drug effects
  • Oxidative Stress / genetics*
  • Protein Folding / drug effects
  • Proteomics*
  • Sodium Compounds / toxicity
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Trichosporon / drug effects
  • Trichosporon / enzymology

Substances

  • Arsenites
  • Sodium Compounds
  • Cadmium
  • sodium arsenite
  • Glutathione Transferase
  • Glutathione

Grants and funding

Prof Sheehan's lab is supported by the Programme for Research in Third Level Institutions of the Higher Education Authority of Ireland. Ms. Ilyas was supported to make a research visit by the International research Initiative Programme of the Higher Education Commission of Pakistan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.