MgrA, an orthologue of Mga, Acts as a transcriptional repressor of the genes within the rlrA pathogenicity islet in Streptococcus pneumoniae.
Streptococcus pneumoniae normally resides in the human nasopharynx in a nondisease state. In response to unknown triggers this organism can descend to the lower respiratory tract and/or invade the bloodstream. Regulation and activation of virulence genes play essential roles in this process of disease development. Characterization of S. pneumoniae regulatory networks has been a recent area of interest, but despite inroads little is known about regulation of virulence genes in this pathogen. A putative transcriptional regulator in S. pneumoniae, mgrA, which exhibits homology to the virulence gene activator mga of group A streptococcus, was previously identified as a regulator that is required for development of pneumonia in a murine model. In this study we confirmed that mgrA plays a role in both nasopharyngeal carriage and pneumonia. Transcriptional profiling by microarray technology was used to show that mgrA acts as a repressor of the previously characterized rlrA pathogenicity islet. This is manifested phenotypically by a decrease in adherence to epithelial cells in tissue culture since the rlrA pathogenicity islet contains genes mediating adherence.
Department of Infectious Diseases, Imperial College, London, United Kingdom.
Carolyn
C
Hemsley
Elizabeth
E
Joyce
David L
DL
Hava
Amita
A
Kawale
Andrew
A
Camilli
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D011018:Pneumonia, Pneumococcal / Q000382:microbiology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014774:Virulence
D001426:Bacterial Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; C470697:rlrA protein, Streptococcus pneumoniae; C068267:mry protein, Streptococcus pyogenes; D012260:Ribonucleases