title: Expression analysis of PCSTE3, a putative pheromone receptor from the lung pathogenic fungus Pneumocystis carinii.
abstract: The fungal pathogen Pneumocystis carinii remains the most prevalent opportunistic infection in patients infected with HIV. Fungal pheromone receptors are seven transmembrane domain G-protein-coupled receptors which are expressed on specific mating types, and have ligand-binding extracellular domains for specific pheromones from cells of the opposite mating type. We have cloned and characterized PCSTE3 from P. carinii, which encodes a seven transmembrane domain protein orthologous to the Saccharomyces cerevisiae pheromone receptor Ste3. We detect PCSTE3 by indirect immunofluorescence using antibodies designed to extracellular domains of the receptor in yeast expressing the protein. Using a downstream Fus1-lacZ reporter gene, we determined that PCSTE3 does not recognize a- or alpha-factor pheromones as ligands for the receptor. We isolated P. carinii life cycle stages and examined PCSTE3 expression by immunofluorescence microscopy and flow cytometry, and found PCSTE3 expression exclusively on a population of trophic forms. PCSTE3 receptor expression was not found on cysts.
authors.affiliation: Thoracic Diseases Research Unit, Division of Pulmonary, Critical Care and Internal Medicine, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Pawan K
authors.initials: PK
authors.lastname: Vohra
authors.forename: John G
authors.initials: JG
authors.lastname: Park
authors.forename: Bharati
authors.initials: B
authors.lastname: Sanyal
authors.forename: Charles F
authors.initials: CF
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D008024:Ligands; D008168:Lung / Q000382:microbiology*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010675:Pheromones / Q000737:chemistry*; D045363:Pneumocystis carinii / Q000235:genetics*; D017434:Protein Structure, Tertiary; D051381:Rats; D043563:Receptors, Pheromone / Q000737:chemistry* / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D018076:DNA, Complementary; D008024:Ligands; C487564:PCSTE3 protein, Pneumocystis jirovecii; D010675:Pheromones; D043563:Receptors, Pheromone