Mycoplasma pneumoniae Community Acquired Respiratory Distress Syndrome toxin expression reveals growth phase and infection-dependent regulation.
Mycoplasma pneumoniae causes acute and chronic respiratory infections, including tracheobronchitis and community acquired pneumonia, and is linked to asthma and an array of extra-pulmonary disorders. Recently, we identified an ADP-ribosylating and vacuolating toxin of M. pneumoniae, designated Community Acquired Respiratory Distress Syndrome (CARDS) toxin. In this study we analysed CARDS toxin gene (annotated mpn372) transcription and identified its promoter. We also compared CARDS toxin mRNA and protein profiles in M. pneumoniae during distinct in vitro growth phases. CARDS toxin mRNA expression was maximal, but at low levels, during early exponential growth and declined sharply during mid-to-late log growth phases, which was in direct contrast to other mycoplasma genes examined. Between 7% and 10% of CARDS toxin was localized to the mycoplasma membrane at mid-exponential growth, which was reinforced by immunogold electron microscopy. No CARDS toxin was released into the medium. Upon M. pneumoniae infection of mammalian cells, increased expression of CARDS toxin mRNA was observed when compared with SP-4 broth-grown cultures. Further, confocal immunofluorescence microscopy revealed that M. pneumoniae readily expressed CARDS toxin during infection of differentiated normal human bronchial epithelial cells. Analysis of M. pneumoniae-infected mouse lung tissue revealed high expression of CARDS toxin per mycoplasma cell when compared with M. pneumoniae cells grown in SP-4 medium alone. Taken together, these studies indicate that CARDS toxin expression is carefully controlled by environmental cues that influence its transcription and translation. Further, the acceleration of CARDS toxin synthesis and accumulation in vivo is consistent with its role as a bona fide virulence determinant.
Kannan
T R
TR
Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
Musatovova
Oxana
O
Balasubramanian
Sowmya
S
Cagle
Marianna
M
Jordan
Jarrat L
JL
Krunkosky
Thomas M
TM
Davis
Alan
A
Hardy
Robert D
RD
Baseman
Joel B
JB
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008171:Lung Diseases / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009177:Mycoplasma pneumoniae / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology / Q000648:ultrastructure; D011019:Pneumonia, Mycoplasma / Q000382:microbiology*; D012333:RNA, Messenger / Q000378:metabolism; D012128:Respiratory Distress Syndrome / Q000382:microbiology*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; C546120:CARDS toxin, Mycoplasma pneumoniae; D012333:RNA, Messenger