Proteomic analysis of differentially expressed Chlamydia pneumoniae genes during persistent infection of HEp-2 cells.
Recent data have shown that the respiratory pathogen Chlamydia pneumoniae expresses an altered gene transcription profile during gamma interferon (IFN-gamma)-induced persistent infection in vitro. In the present study, we examined, by proteomics, expression of C. pneumoniae proteins labeled intracellularly with [(35)S]methionine/cysteine under normal conditions or IFN-gamma-mediated persistence. The identity of differentially expressed proteins during persistent infection was determined by matching spots to those of proteins identified in C. pneumoniae elementary bodies by matrix-assisted laser desorption ionization mass spectrometry. Upon treatment with 50 U of IFN-gamma per ml, a marked upregulation of major outer membrane protein (MOMP), heat shock protein 60 (Hsp-60/GroEL), and proteins with functions in DNA replication (GyrA), transcription (RpoA, PnP), translation (Rrf), glycolysis (PgK, GlgP), and type III secretion (SctN) was observed at 24 h of infection. In contrast, no significant decreases in bacterial protein expression were found in C. pneumoniae-infected cells due to IFN-gamma treatment. Upregulation of C. pneumoniae proteins involved in diverse functions during persistent infection may allow the organism to resist the inhibitory effects of IFN-gamma while retaining basic functions. Future studies should examine the differential expression of chlamydial proteins during the developmental cycle under IFN-gamma pressure to obtain a finer representation of the gene products involved in establishing persistence.
Molestina
Robert E
RE
Division of Infectious Diseases, Department of Medicine, University of Louisville School of Medicine, University of Louisville, Louisville, Kentucky 40292, USA.
Klein
Jon B
JB
Miller
Richard D
RD
Pierce
William H
WH
Ramirez
Julio A
JA
Summersgill
James T
JT
D001426:Bacterial Proteins / Q000032:analysis*; D002690:Chlamydia Infections / Q000382:microbiology; D016993:Chlamydophila pneumoniae / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D015870:Gene Expression; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D014407:Tumor Cells, Cultured
D001426:Bacterial Proteins; D020543:Proteome; D007371:Interferon-gamma