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Complementation and characterization of the Pneumocystis carinii MAPK, PCM
Author(s) -
Vohra Pawan K.,
Puri Veenu,
Thomas Charles F.
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)00914-1
Subject(s) - pneumocystis carinii , mapk/erk pathway , biology , protein kinase a , microbiology and biotechnology , signal transduction , kinase , biochemistry , pneumocystis jirovecii , immunology , human immunodeficiency virus (hiv)
Mitogen‐activated protein kinase (MAPK) pathways transfer environmental signals into intracellular events such as proliferation and differentiation. Fungi utilize a specific pheromone‐induced MAPK pathway to regulate conjugation, formation of an ascus, and entry into meiosis. We have previously identified a MAPK, PCM, from the fungal opportunist Pneumocystis , responsible for causing severe pneumonia in patients with AIDS. In order to gain insight into the function of PCM, we expressed it in Saccharomyces cerevisiae deficient in pheromone signaling and tested activation and inhibition of this MAPK pathway. PCM restored pheromone signaling in S. cerevisiae fus3 Δ kss1 Δ mutants with α‐factor pheromone (six‐fold increase) and was not activated by osmotic stress. Signaling through this pathway decreased 2.5‐fold with 10 μM U0126, and was unaffected with SB203580. We evaluated the conditions for native PCM kinase activity isolated from Pneumocystis carinii organisms and found that 0.1 mM MgCl 2 , pH 6.5, temperature 30–35°C, and 10 μM ATP were optimal. The activity of PCM is significantly elevated in P. carinii trophic forms compared to cysts, implicating a role for PCM in the life cycle transition of P. carinii from trophic forms to cysts.