The Haemophilus influenzae dprABC genes constitute a competence-inducible operon that requires the product of the tfoX (sxy) gene for transcriptional activation.
We previously showed that dprA is required for efficient processing of linear DNA during cellular transformation in Haemophilus influenzae. In this study the transcriptional regulation of dprA and two downstream genes, dprB and dprC, is examined. We demonstrate by Northern blot analysis that the dprABC genes are transcriptionally coregulated and competence inducible. We used primer extension analysis to map the transcriptional start site of dprA and of rec-2, another transformation gene involved in DNA processing. Based upon these results, we were able to identify a 26-bp dyad symmetry element immediately upstream of the -35 regions of the predicted promoters of dprA, rec-2, and two other transformation genes, comA and pilA. Finally, using transcriptional fusions of dprA to the Escherichia coli lacZ gene, we show that expression of dprA::lacZ requires tfoX and that the presence of multiple copies of tfoX abolishes the temporal regulation of dprA, resulting in its constitutive expression.
Karudapuram
S
S
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
Barcak
G J
GJ
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006193:Haemophilus influenzae / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics*; D009876:Operon; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D017931:DNA Primers; C093815:DprA protein, bacteria; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C000602560:Sxy protein, E coli; C093149:Tfox protein, Haemophilus influenzae; D015534:Trans-Activators; C088949:rec-2 protein, Haemophilus influenzae