Importance of mitochondria in survival of Cryptococcus neoformans under low oxygen conditions and tolerance to cobalt chloride.

Abstract

Cryptococcus neoformans is an environmental fungal pathogen that requires atmospheric levels of oxygen for optimal growth. For the fungus to be able to establish an infection, it must adapt to the low oxygen concentrations in the host environment compared to its natural habitat. In order to investigate the oxygen sensing mechanism in C. neoformans, we screened T-DNA insertional mutants for hypoxia-mimetic cobalt chloride (CoCl(2))-sensitive mutants. All the CoCl(2)-sensitive mutants had a growth defect under low oxygen conditions at 37 degrees C. The majority of mutants are compromised in their mitochondrial function, which is reflected by their reduced rate of respiration. Some of the mutants are also defective in mitochondrial membrane permeability, suggesting the importance of an intact respiratory system for survival under both high concentrations of CoCl(2) as well as low oxygen conditions. In addition, the mutants tend to accumulate intracellular reactive oxygen species (ROS), and all mutants show sensitivity to various ROS generating chemicals. Gene expression analysis revealed the involvement of several pathways in response to cobalt chloride. Our findings indicate cobalt chloride sensitivity and/or sensitivity to low oxygen conditions are linked to mitochondrial function, sterol and iron homeostasis, ubiquitination, and the ability of cells to respond to ROS. These findings imply that multiple pathways are involved in oxygen sensing in C. neoformans.

• Authors: Susham S Ingavale, Yun C Chang, Hyeseung Lee, Carol M McClelland, Madeline L Leong, Kyung J Kwon-Chung
• Journal: PLoS pathogens (PLoS Pathog) Vol. 4 Issue 9 Pg. e1000155 (Sep 19 2008) ISSN: 1553-7374 [Electronic] United States
• PMID: 18802457 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)

Chemical References

• Reactive Oxygen Species
• Cobalt
• cobaltous chloride

Topics

• Adaptation, Physiological
• Anaerobiosis
• Cobalt (pharmacology)
• Cryptococcus neoformans (metabolism, physiology)
• Gene Expression Profiling
• Gene Expression Regulation, Fungal (drug effects)
• Metabolic Networks and Pathways
• Microbial Viability
• Mitochondria (physiology)
• Reactive Oxygen Species (metabolism)