title: Pneumocystis encodes a functional endo-β-1,3-glucanase that is expressed exclusively in cysts.
abstract: β-1,3-glucan is a major cell wall component of Pneumocystis cysts. We have characterized endo-β-1,3-glucanase (Eng) from 3 species of Pneumocystis. The gene eng is a single-copy gene that encodes a protein containing 786 amino acids in P. carinii and P. murina, and 788 amino acids in P. jirovecii, including a signal peptide for the former 2 but not the latter. Recombinant Eng expressed in Escherichia coli was able to solubilize the major surface glycoprotein of Pneumocystis, thus potentially facilitating switching of the expressed major surface glycoprotein (Msg) variant. Confocal immunofluorescence analysis of P. murina-infected mouse lung sections localized Eng exclusively to the cyst form of Pneumocystis. No Eng was detected after mice were treated with caspofungin, a β-1,3-glucan synthase inhibitor that is known to reduce the number of cysts. Thus, Eng is a cyst-specific protein that may play a role in Msg variant expression in Pneumocystis.
authors.affiliation: Critical Care Medicine Department, National Institutes of Health Clinical Center.
authors.forename: Geetha
authors.initials: G
authors.lastname: Kutty
authors.affiliation: Viral Pathogenesis and Evolution Section, Laboratory of Infectious Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland.
authors.forename: A Sally
authors.initials: AS
authors.lastname: Davis
authors.affiliation: Critical Care Medicine Department, National Institutes of Health Clinical Center.
authors.forename: Liang
authors.initials: L
authors.lastname: Ma
authors.affiliation: Viral Pathogenesis and Evolution Section, Laboratory of Infectious Disease, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland.
authors.forename: Jeffery K
authors.initials: JK
authors.lastname: Taubenberger
authors.affiliation: Critical Care Medicine Department, National Institutes of Health Clinical Center.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Kovacs
mesh_terms: D000818:Animals; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D015966:Gene Expression Regulation, Fungal; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000096:biosynthesis* / Q000235:genetics; D008168:Lung / Q000382:microbiology / Q000473:pathology; D051379:Mice; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011010:Pneumocystis / Q000201:enzymology* / Q000235:genetics; D021382:Protein Sorting Signals / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013172:Spores, Fungal / Q000201:enzymology* / Q000235:genetics
chemical_list: D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D004693:Glucan Endo-1,3-beta-D-Glucosidase
keywords: Eng; Pneumocystis; cell wall; endo-β-1,3-glucanase; glucan