Characterization of a Ferrous Iron-Responsive Two-Component System in Nontypeable Haemophilus influenzae

Steele, Kendra H.; O’Connor, Lauren H.; Burpo, Nicole; Köhler, Katharina; Johnston, Jason W.

doi:10.1128/jb.01465-12

Cited by 36 publications

(55 citation statements)

References 91 publications

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“…Examination of the 137 bp intergenic region that resides between ygiW and qseB identified a putative attenuator region (see Fig. S1, available in Microbiology Online), consistent with the structure of the ygiW-firRS operon recently reported in Haemophilus influenzae (Steele et al, 2012). Strains that were transformed with pDJR30, pDJR31, pDJR33 and the promoterless control plasmid pJT3 expressed no measurable b-gal activity.…”

Section: The Promoter Region Of the Ygiw-qsebc Operon Resides Within supporting

confidence: 82%

ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth

2013

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The quorum-sensing Escherichia coli regulators B and C (QseBC) two-component system were previously shown to regulate biofilm growth of the oral pathogen Aggregatibacter actinomycetemcomitans and to be essential for virulence. In this study, we use RT-PCR to show that an open reading frame, ygiW, residing upstream of qseBC and encoding a hypothetical protein is co-expressed with qseBC. In addition, using a series of lacZ transcriptional fusion constructs and 59-rapid amplification of cDNA Ends (RACE), the promoter that drives expression of the ygiW-qseBC operon and the transcriptional start site was mapped to the 372 bp intergenic region upstream from ygiW. No internal promoters drive qseBC expression independently from ygiW. However, qseBC expression is attenuated by approximately ninefold by a putative attenuator stem-loop (DG5"77.0 KJ/mol) that resides in the 137 bp intergenic region between ygiW and qseB. The QseB response regulator activates expression of the ygiW-qseBC operon and transcription from the ygiW promoter is drastically reduced in DqseB and DqseBC mutants of A. actinomycetemcomitans. In addition, transcriptional activity of the ygiW promoter is significantly reduced in a mutant expressing an in-frame deletion of qseC that lacks the sensor domain of QseC, suggesting that a periplasmic signal is required for QseB activation. Finally, a non-polar inframe deletion in ygiW had little effect on biofilm depth but caused a significant increase in surface coverage relative to wild-type. Complementation of the mutant with a plasmid-borne copy of ygiW reduced surface coverage back to wild-type levels. Interestingly, deletion of the sensor domain of QseC or of the entire qseC open reading frame resulted in significant reductions in biofilm depth, biomass and surface coverage, indicating that the sensor domain is essential for optimal biofilm formation by A. actinomycetemcomitans. Thus, although ygiW and qseBC are coexpressed, they regulate biofilm growth by distinct mechanisms. INTRODUCTIONAggregatibacter actinomycetemcomitans is a Gram-negative, facultative anaerobe of the Pasteurellaceae family and is the primary aetiological agent of localized aggressive periodontitis and severe non-oral infections, including endocarditis, soft tissue abscesses, meningitis, pneumonia, septicaemia, urinary tract infections and osteomyelitis (Haffajee & Socransky, 1994; Hyvärinen et al., 2012;Henderson et al., 2003;Nørskov-Lauritsen & Kilian, 2006;Paturel et al., 2004;Rahamat-Langendoen et al., 2011;Wang et al., 2010). The molecular mechanisms involved in A. actinomycetemcomitans virulence and pathogenesis are not well defined, but A. actinomycetemcomitans expresses two autotransporter adhesins (Aae and ApiA) and fimbriae (encoded by the tad locus) that are involved in the colonization and formation of biofilms on oral tissues (Fine et al., 2010;Perez et al., 2006;Saito et al., 2010;Yue et al., 2007). In addition, the organism expresses virulence factors that target the innate immune response to infection, including a leuk...

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Section: The Promoter Region Of the Ygiw-qsebc Operon Resides Within supporting

confidence: 82%

ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth

2013

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“…1A). The 24 genes required in single infection but not in coinfection included several in the pathway for histidine biosynthesis (hisG, D,A,F), the tricarboxylic acid cycle [malate dehydrogenase (mdh)] and electron transport chain [Na(+)-translocating NADH-quinone reductase subunit C (nqrC)] (18), and a sensor of ferrous iron (firS) (19 (25). DNA excision and mismatch repair genes that may be protective against these stresses were implicated [DNA polymerase III subunit psi (holD), transcription-repair coupling factor (mfd), DNA-dependent helicase II (uvrD)].…”

Section: Iavmentioning

confidence: 99%

Genome-wide fitness profiling reveals adaptations required by Haemophilus in coinfection with influenza A virus in the murine lung

Wong

Bernui

Shen

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Bacterial coinfection represents a major cause of morbidity and mortality in epidemics of influenza A virus (IAV). The bacterium Haemophilus influenzae typically colonizes the human upper respiratory tract without causing disease, and yet in individuals infected with IAV, it can cause debilitating or lethal secondary pneumonia. Studies in murine models have detected immune components involved in susceptibility and pathology, and yet few studies have examined bacterial factors contributing to coinfection. We conducted genome-wide profiling of the H. influenzae genes that promote its fitness in a murine model of coinfection with IAV. Application of direct, high-throughput sequencing of transposon insertion sites revealed fitness phenotypes of a bank of H. influenzae mutants in viral coinfection in comparison with bacterial infection alone. One set of virulence genes was required in nonvirally infected mice but not in coinfection, consistent with a defect in anti-bacterial defenses during coinfection. Nevertheless, a core set of genes required in both in vivo conditions indicated that many bacterial countermeasures against host defenses remain critical for coinfection. The results also revealed a subset of genes required in coinfection but not in bacterial infection alone, including the iron-sulfur cluster regulator gene, iscR, which was required for oxidative stress resistance. Overexpression of the antioxidant protein Dps in the iscR mutant restored oxidative stress resistance and ability to colonize in coinfection. The results identify bacterial stress and metabolic adaptations required in an IAV coinfection model, revealing potential targets for treatment or prevention of secondary bacterial pneumonia after viral infection.transposon-insertion sequencing | functional genomics

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“…Most notably, the DesK/DesR TCS of Bacillus subtilis has been shown to respond to a temperature downshift and subsequently activate the transcription of an O 2 -dependent membrane lipid desaturase-encoding des, resulting in increased membrane fluidity (7,8). In addition, cold-related TCSs have been identified in Listeria monocytogenes (9), Haemophilus influenzae (10), the archaeon Methanolobus psychrophilus R15 (11), and Yersinia pseudotuberculosis (12).…”

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confidence: 99%

The Cold-Induced Two-Component System CBO0366/CBO0365 Regulates Metabolic Pathways with Novel Roles in Group I Clostridium botulinum ATCC 3502 Cold Tolerance

Dahlsten

Zhang

Somervuo

et al. 2014

Appl Environ Microbiol

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bThe two-component system CBO0366/CBO0365 was recently demonstrated to have a role in cold tolerance of group I Clostridium botulinum ATCC 3502. The mechanisms under its control, ultimately resulting in increased sensitivity to low temperature, are unknown. A transcriptomic analysis with DNA microarrays was performed to identify the differences in global gene expression patterns of the wild-type ATCC 3502 and a derivative mutant with insertionally inactivated cbo0365 at 37 and 15°C. Altogether, 150 or 141 chromosomal coding sequences (CDSs) were found to be differently expressed in the cbo0365 mutant at 37 or 15°C, respectively, and thus considered to be under the direct or indirect transcriptional control of the response regulator CBO0365. Of the differentially expressed CDSs, expression of 141 CDSs was similarly affected at both temperatures investigated, suggesting that the putative CBO0365 regulon was practically not affected by temperature. The regulon involved genes related to acetone-butanol-ethanol (ABE) fermentation, motility, arsenic resistance, and phosphate uptake and transport. Deteriorated growth at 17°C was observed for mutants with disrupted ABE fermentation pathway components (crt, bcd, bdh, and ctfA), arsenic detoxifying machinery components (arsC and arsR), or phosphate uptake mechanism components (phoT), suggesting roles for these mechanisms in cold tolerance of group I C. botulinum. Electrophoretic mobility shift assays showed recombinant CBO0365 to bind to the promoter regions of crt, arsR, and phoT, as well as to the promoter region of its own operon, suggesting direct DNA-binding transcriptional activation or repression as a means for CBO0365 in regulating these operons. The results provide insight to the mechanisms group I C. botulinum utilizes in coping with cold.

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Characterization of a Ferrous Iron-Responsive Two-Component System in Nontypeable Haemophilus influenzae

Cited by 36 publications

References 91 publications

ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth

ygiW and qseBC are co-expressed in Aggregatibacter actinomycetemcomitans and regulate biofilm growth

Genome-wide fitness profiling reveals adaptations required by Haemophilus in coinfection with influenza A virus in the murine lung

The Cold-Induced Two-Component System CBO0366/CBO0365 Regulates Metabolic Pathways with Novel Roles in Group I Clostridium botulinum ATCC 3502 Cold Tolerance

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