Characterization of the expression site of the major surface glycoprotein of human-derived Pneumocystis carinii

Citation
G. Kutty et al., Characterization of the expression site of the major surface glycoprotein of human-derived Pneumocystis carinii, MOL MICROB, 42(1), 2001, pp. 183-193
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
1
Year of publication
2001
Pages
183 - 193
Database
ISI
SICI code
0950-382X(200110)42:1<183:COTESO>2.0.ZU;2-6
Abstract
The major surface glycoprotein (MSG) of Pneumocystis carinii, a pathogen re sponsible for pulmonary infection in AIDS and other immunocompromised patie nts, is an abundant surface protein that potentially allows the organism to evade host defences by antigenic variation. MSG is encoded by a multicopy gene family; in two specific forms of rat-derived P. carinii, regulation of MSG expression uses a single expression site, termed the upstream conserve d sequence (UCS), through two related but distinct mechanisms. In the curre nt study, the UCS of the from human-derived P. carinii was obtained using a n RNA ligase-mediated rapid amplification of cDNA ends technique. Southern blot analysis demonstrated that the UCS was present in a single copy per ge nome, whereas multiple copies of the downstream MSG gene were present. Sequ encing and restriction fragment length polymorphism analysis of polymerase chain reaction products amplified from pulmonary samples of patients with P . carinii pneumonia demonstrated that multiple MSG genes were expressed in a given host, and that different patterns of MSG expression were seen among different patients. Tandem repeats present in the single intron occurred w ith varying frequency in different patient isolates, potentially providing a new method for typing human isolates. Thus, human-derived P. carinii regu lates MSG expression in a manner similar to P. carinii f. sp. carinii and, in immunosuppressed patients, in whom immune pressures that probably drive antigenic variation are functioning inadequately, P. carinii can express a broad repertoire of MSG variants.