Pneumocystis Encodes a Functional Endo-β-1,3-glucanase that is Expressed Exclusively in Cysts.

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Pneumocystis Encodes a Functional Endo-β-1,3-glucanase that is Expressed Exclusively in Cysts.

J Infect Dis. 2014 Sep 17;

Authors: Kutty G, Davis AS, Ma L, Taubenberger JK, Kovacs JA

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. eng is a single copy gene which 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 E. coli was able to solubilize the major surface glycoprotein of Pneumocystis, thus potentially facilitating switching of the expressed 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.

PMID: 25231017 [PubMed - as supplied by publisher]