Transcriptional profiling ofBordetella pertussisreveals requirement of RNA chaperone Hfq for Type III secretion system functionality

Abstract

Bordetella pertussis, the causative agent of human whooping cough (pertussis) produces a complex array of virulence factors in order to establish efficient infection in the host. The RNA chaperone Hfq and small regulatory RNAs are key players in posttranscriptional regulation in bacteria and have been shown to play an essential role in virulence of a broad spectrum of bacterial pathogens. This study represents the first attempt to characterize the Hfq regulon of the human pathogen B. pertussis under laboratory conditions as well as upon passage in the host and indicates that loss of Hfq has a profound effect on gene expression in B. pertussis. Comparative transcriptional profiling revealed that Hfq is required for expression of several virulence factors in B. pertussis cells including the Type III secretion system (T3SS). In striking contrast to the wt strain, T3SS did not become operational in the hfq mutant passaged either through mice or macrophages thereby proving that Hfq is required for the functionality of the B. pertussis T3SS. Likewise, expression of virulence factors vag8 and tcfA encoding autotransporter and tracheal colonization factor, respectively, was strongly reduced in the hfq mutant. Importantly, for the first time we demonstrate that B. pertussis T3SS can be activated upon contact with macrophage cells in vitro.

Signal transduction-dependent small regulatory RNA is involved in glutamate metabolism of the human pathogen Bordetella pertussis

“…In this respect, the RgtA-dependent reduction of BP3831 levels may help the pathogen to adapt to new sources of nutrients (other than glutamate) and/or decrease the antigenicity by reduction of the amounts of immunogenic protein. In support, the expression of BP3831 was significantly reduced in mousepassaged B. pertussis cells recovered 12 d post infection (Bibova et al 2015). Furthermore, glutamate starvation was shown to result in reduced production of virulence factors (Nakamura et al 2006) and may be then considered as a signal to reprogram the metabolism in order to persist within the host.…”

“…We have shown that the Hfq protein significantly affects the expression of more than 10% of the B. pertussis genes (Bibova et al 2015) and that the Hfq protein is required for B. pertussis virulence (Bibova et al 2013). These observations suggested that sRNAs could play an important role in the physiological fitness of this pathogen.…”

“…Purified RNA was checked for concentration and integrity using the Bioanalyzer 2100 device (Agilent Technologies). Labeling with Cyanine-5 and Cyanine-3 was performed as already described (Bibova et al 2015). For each sample, a Cy5/Cy3 dyeswap technical replicate starting from the same RNA preparation was prepared and hybridized with DNA oligonucleotide probes spotted onto microarray slides for 14 to 16 h at 52°C under agitation.…”

Post-transcriptional regulation of type III secretion in plant and animal pathogens

“…Hfq can exert both negative and positive effects on T3SS gene expression though few direct mechanisms have been defined [27–30]. S. enterica hilD is positively influenced by Hfq and likely interacts with the 3′ UTR of hilD [31,32].…”

Post-transcriptional regulation of virulence factors in Pseudomonas aeruginosa

“…Hfq is an RNA chaperone that promotes base pairing between small non-coding regulatory sRNAs and mRNA targets [253]. Hfq can exert both negative and positive effects on T3SS gene expression [145,[270][271][272]. S. enterica hilD is positively influenced by Hfq and likely interacts with the 3' UTR of hilD [273,274].…”