Project description:Non-typeable Haemophilus influenzae (NTHi) contains an N6-adenine DNA-methyltransferase (ModA), that is subject to phase variable expression (random ON/OFF switching). Five modA alleles, modA2, 4, 5, 9 and 10, account for over two-thirds of clinical otitis media isolates surveyed. Single Molecule Real Time (SMRT) methylome analysis identified the DNA recognition motifs for all five of these modA alleles. Phase variation of these alleles regulated multiple proteins, including vaccine candidates. ON/OFF switching of modA alleles resulted in differential regulation of key virulence phenotypes, such as antibiotic resistance (modA2, 5, 10), biofilm formation (modA2) and immunoevasion (modA4). Analysis of the modA2 strain, 723, in the chinchilla model of otitis media showed a clear selection for switching from modA2OFF to ON in the middle ear. This is the first report of a biphasic epigenetic switch controlling bacterial virulence, immunoevasion and niche adaptation in an animal model system Direct comparison of biological triplicates of wild type and mutant strains
Project description:iTRAQ quantitative mass spec of proteins differentially regulated by biphasic switching of modA methyltransferase alleles in the human pathogen non-typeable Haemophilus influenzae
Project description:Non-typeable Haemophilus influenzae (NTHi) contains an N6-adenine DNA-methyltransferase (ModA), that is subject to phase variable expression (random ON/OFF switching). Five modA alleles, modA2, 4, 5, 9 and 10, account for over two-thirds of clinical otitis media isolates surveyed. Single Molecule Real Time (SMRT) methylome analysis identified the DNA recognition motifs for all five of these modA alleles. Phase variation of these alleles regulated multiple proteins, including vaccine candidates. ON/OFF switching of modA alleles resulted in differential regulation of key virulence phenotypes, such as antibiotic resistance (modA2, 5, 10), biofilm formation (modA2) and immunoevasion (modA4). Analysis of the modA2 strain, 723, in the chinchilla model of otitis media showed a clear selection for switching from modA2OFF to ON in the middle ear. This is the first report of a biphasic epigenetic switch controlling bacterial virulence, immunoevasion and niche adaptation in an animal model system
Project description:Characterization of a novel haem-binding protein produced by Haemophilus haemolyticus, isolated and purified from non-typeable Haemophilus influenzae (NTHi)-inhibitory substance.
Project description:Characterization of a novel haem-binding protein that is secreted by two Haemophilus haemolyticus isolates, BW1 and RHH122, and that inhibits the growth of the pathogen non-typeable Haemophilus influenzae (NTHi) in vitro.
Project description:Background: Haemophilus influenzae has an absolute aerobic growth requirement for heme and has developed multiple complex mechanisms to obtain this essential nutrient. Although an understanding of the heme acquisition mechanisms of H. influenzae is emerging, significant gaps remain to be elucidated. In a previous study we utilized H. influenzae strain Rd KW20 to demonstrate the utility of transcriptional profiling in defining the genes exhibiting altered transcription in response to environmental iron and heme levels. The current study expands upon those initial observations by determining the iron/heme regulons of two additional H. influenzae clinical isolates, i.e. the type b isolate 10810 and the nontypeable isolate R2866, to characterize the core iron/heme regulon of the species. Results: A microarray chip was designed to incorporate probes for all of the genes of H. influenzae isolates 10810 and R2866, and microarray studies were performed to compare gene expression under iron/heme-replete and iron/heme-restricted conditions for each isolate. Of 1820 ORFs on the array corresponding to R2866 genes, 363 were significantly differentially expressed. Of these 363 genes, 233 were maximally transcribed under iron/heme-replete conditions and 130 were preferentially transcribed in iron/heme-restricted conditions. Of the 1883 ORFs representing genes of strain10810, 351 were significantly differentially transcribed, 150 of these were preferentially transcribed in iron/heme-replete conditions and 201 were preferentially transcribed in iron/heme-restricted conditions. Comparison of the data sets indicated that 163 genes were similarly regulated in both isolates and that 74 of these also exhibited similar patterns of regulation in strain Rd KW20. Conclusion: This study provides evidence for a core of H. influenzae genes that are regulated by the availability of iron and/or heme in the growth environment. Elucidation of this core regulon provides targets for investigation of genes with an unrecognized role in iron and heme homeostasis, as well as other potential virulence determinants. In addition, the set of core genes potentially provides targets for therapeutic and vaccine designs since these products of these genes are likely to be preferentially expressed during growth in iron/heme restricted sites of the human body. This SuperSeries is composed of the following subset Series: GSE11349: Transcriptional profiling of FeHm effects on Haemophilus influenzae R2866 GSE11354: Transcriptional profiling of FeHm effects on Haemophilus influenzae 10810 Keywords: SuperSeries Refer to individual Series
