Several studies have revealed the role of Hfq and sRNAs in post-t

Several studies have revealed the role of Hfq and sRNAs in post-transcriptional regulation of iron responsive genes [18–20]. Hfq is found in many bacterial

pathogens and is a pleiotropic gene regulator; mutants exhibit phenotypes including defects in virulence, growth rates, stress tolerance and biofilm formation [21]. The phenotypes of hfq mutants vary greatly between bacterial species because of the wide array of RNA with which Hfq interacts [17]. Here we report the characterization of a deletion mutant of hfq in H. influenzae. We demonstrate in vitro that Hfq is important in modulating Selleckchem NVP-AUY922 the utilization of heme from hemoglobin. Further we show that Hfq plays a role in pathogenesis in the infant

rat and chinchilla models of disease. Thus, Hfq may be modulating nutrient utilization systems that allow H. influenzae to better adapt to niches within the host during infection. Methods Bacterial strains and growth conditions Nontypeable H. influenzae strain R2866 is a clinical isolate from the blood of an immunocompetent pediatric patient with clinical signs of meningitis following acute OM [22]. Nontypeable H. influenzae strain 86-028NP was isolated from the nasopharynx of a child being treated for chronic OM who underwent tympanostomy and tube insertion [23, 24]. H. influenzae strains were routinely grown on chocolate agar PF 2341066 with bacitracin at 37°C. H. influenzae was also cultured on brain heart infusion (BHI) agar or in BHI broth supplemented with 10 μg mL-1 heme and 10 μg mL-1 β-NAD (supplemented BHI; sBHI) or BHI supplemented with 10 μg mL-1 β-NAD (heme deplete BHI; hdBHI). The antibiotics spectinomycin (200 μg mL-1) and chloramphenicol (2.0 μg mL-1) were used when appropriate. Heme sources Human hemoglobin and heme (as hemin) were purchased from Sigma. Stock heme solutions were prepared at 1.0 mg mL-1 heme TCL in 4% v/v triethanolamine as previously described [25]. Hemoglobin was dissolved in water immediately before use. Construction of the hfq mutant

A deletion mutant lacking the entire hfq gene was constructed using two pairs of primers to amplify regions upstream and downstream of hfq by PCR using strain R2866 DNA as template. Primer pair Hfq_US1 (GAATTCGATTTGTTAGGAAAGCCTGCC) and Hfq_US2 (GGATCCGCGGTTGAAAATTCTCAGGAAA) was used to amplify an 867-bp fragment upstream of hfq with EcoRI and BamHI restriction sites engineered into the primers, respectively, to allow for directional subcloning. Hfq_DS1 (GGATCCAGAAACGAGTTGTCTCCGTG) and Hfq_DS2 (AAGCTTCGAAGTGCGAGTAAACAAAGGC) were used to amplify an 869-bp fragment downstream of hfq with BamHI and HindIII restriction sites incorporated into the primers, respectively. The PCR products were cloned into the TA cloning vector pCR2.1-TOPO (Invitrogen) and the cloned sequences were confirmed by DNA sequencing.

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