Affiliation:
1. Thoracic Diseases Research Unit, Division of Pulmonary, Critical Care and Internal Medicine
2. Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905
Abstract
ABSTRACT
Pneumocystis
continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in
Pneumocystis
. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from
Pneumocystis
and melanized
Pneumocystis
cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across
Pneumocystis
host species, including mouse-, ferret-, and human-derived
Pneumocystis
organisms, as well as
Pneumocystis carinii
derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of
P. carinii
cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of
Pneumocystis
viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of
Pneumocystis
, we observed that strongly melanized
Pneumocystis
retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of
Pneumocystis
melanins across the genus, further characterize these
Pneumocystis
components, and demonstrate that melanins protect
Pneumocystis
from environmental stressors.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology
Cited by
9 articles.
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