Evolution of Bacterial Global Modulators: Role of a Novel H-NS Paralogue in the Enteroaggregative
            <i>Escherichia coli</i>
            Strain 042

Prieto, Alejandro; Bernabeu, Manuel; Aznar, Salvador; Ruiz‐Cruz, Sofía; Bravo, Alicia; Queiroz, Mário H.; Juárez, Antonio

doi:10.1128/msystems.00220-17

Cited by 13 publications

(26 citation statements)

References 50 publications

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“…), indicated that, although H‐NS marginally represses both promoters, AggR still substantially activates transcription in the absence of H‐NS. Consistent with this, a recent transcriptomic analysis in EAEC 042 indicated that neither afaB nor aafD were derepressed by the absence of H‐NS or its homologue H‐NS2 (EC042_2824) (Prieto et al , ). Therefore, we propose that, at the afaB and aafD promoters, AggR primarily activates transcription by directly interacting with RNA polymerase rather than alleviating H‐NS repression.…”

Section: Discussionmentioning

confidence: 69%

Organization and architecture of AggR‐dependent promoters from enteroaggregative Escherichia coli

Yasir

Icke

Abdelwahab

et al. 2018

Molecular Microbiology

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Summary Enteroaggregative Escherichia coli (EAEC), is a diarrhoeagenic human pathogen commonly isolated from patients in both developing and industrialized countries. Pathogenic EAEC strains possess many virulence determinants, which are thought to be involved in causing disease, though, the exact mechanism by which EAEC causes diarrhoea is unclear. Typical EAEC strains possess the transcriptional regulator, AggR, which controls the expression of many virulence determinants, including the attachment adherence fimbriae (AAF) that are necessary for adherence to human gut epithelial cells. Here, using RNA‐sequencing, we have investigated the AggR regulon from EAEC strain 042 and show that AggR regulates the transcription of genes on both the bacterial chromosome and the large virulence plasmid, pAA2. Due to the importance of fimbriae, we focused on the two AAF/II fimbrial gene clusters in EAEC 042 (afaB‐aafCB and aafDA) and identified the promoter elements and AggR‐binding sites required for fimbrial expression. In addition, we examined the organization of the fimbrial operon promoters from other important EAEC strains to understand the rules of AggR‐dependent activation. Finally, we generated a series of semi‐synthetic promoters to define the minimal sequence required for AggR‐mediated activation and show that the correct positioning of a single AggR‐binding site is sufficient to confer AggR‐dependence.

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Section: Discussionmentioning

confidence: 69%

Organization and architecture of AggR‐dependent promoters from enteroaggregative Escherichia coli

Yasir

Icke

Abdelwahab

et al. 2018

Molecular Microbiology

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“…Histone‐like nucleoid‐structuring protein (H‐NS), one of the global regulators of transcription, plays roles enabling bacterial cells to adapt to a changing environment . H‐NS consists of 137 amino acid residues with oligomerization and DNA‐binding domains.…”

Section: Introductionmentioning

confidence: 99%

H‐NS, IHF, and DnaA lead to changes in nucleoid organizations, replication initiation, and cell division

et al. 2019

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Histone-like nucleoid-structuring protein (H-NS) and integration host factor (IHF) are major nucleoid-associated proteins, and DnaA, a replication initiator, may also be related with nucleoid compaction. It has been shown that proteindependent DNA compaction is related with many aspects of bacterial physiology, including transcription, DNA replication, and site-specific recombination. However, the mechanism of bacterial physiology resulting from nucleoid compaction remains unknown. Here, we show that H-NS is important for correct nucleoid compaction in a medium-independent manner. H-NSmediated nucleoid compaction is not required for correct cell division, but the latter is dependent on H-NS in rich medium. Further, it is found that the IHFαmediated nucleoid compaction is needed for correct cell division, and the effect is dependent on medium. Also, we show that the effects of H-NS and IHF on nucleoid compaction are cumulative. Interestingly, DnaA also plays an important role in nucleoid compaction, and the effect of DnaA on nucleoid compaction appears to be related to cell division in a medium-dependent manner. The results presented here suggest that scrambled initiation of replication, improper cell division, and slow growth is likely associated with disturbances in nucleoid organization directly or indirectly.

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“…StpA, Hfp and Sfh (HppH) bind to many of the same chromosomal loci as H-NS in E. coli and Salmonella ( 3 , 27 , 40 ). The DNA binding domain (T110–A117) is 100% conserved within the H-NS clade and largely conserved across the homolog clades (Figure 3D ).…”

Section: Resultsmentioning

confidence: 99%

“…Also problematic is that a mix of manual and automated genome annotations according to top BLAST hits has resulted in H-NS homologs with multiple names in use (e.g. Hfp and HNS2) ( 26 , 40 ), or multiple homologs in a genome all being classified as H-NS. Thus, gene and protein names may not accurately reflect evolutionary and functional relatedness.…”

Section: Introductionmentioning

confidence: 99%

Redefining the H-NS protein family: a diversity of specialized core and accessory forms exhibit hierarchical transcriptional network integration

Fitzgerald

Kary

Alshabib

et al. 2020

Nucleic Acids Research

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H-NS is a nucleoid structuring protein and global repressor of virulence and horizontally-acquired genes in bacteria. H-NS can interact with itself or with homologous proteins, but protein family diversity and regulatory network overlap remain poorly defined. Here, we present a comprehensive phylogenetic analysis that revealed deep-branching clades, dispelling the presumption that H-NS is the progenitor of varied molecular backups. Each clade is composed exclusively of either chromosome-encoded or plasmid-encoded proteins. On chromosomes, stpA and newly discovered hlpP are core genes in specific genera, whereas hfp and newly discovered hlpC are sporadically distributed. Six clades of H-NS plasmid proteins (Hpp) exhibit ancient and dedicated associations with plasmids, including three clades with fidelity for plasmid incompatibility groups H, F or X. A proliferation of H-NS homologs in Erwiniaceae includes the first observation of potentially co-dependent H-NS forms. Conversely, the observed diversification of oligomerization domains may facilitate stable co-existence of divergent homologs in a genome. Transcriptomic and proteomic analysis in Salmonella revealed regulatory crosstalk and hierarchical control of H-NS homologs. We also discovered that H-NS is both a repressor and activator of Salmonella Pathogenicity Island 1 gene expression, and both regulatory modes are restored by Sfh (HppH) in the absence of H-NS.

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Evolution of Bacterial Global Modulators: Role of a Novel H-NS Paralogue in the Enteroaggregative Escherichia coli Strain 042

Cited by 13 publications

References 50 publications

Organization and architecture of AggR‐dependent promoters from enteroaggregative Escherichia coli

Organization and architecture of AggR‐dependent promoters from enteroaggregative Escherichia coli

H‐NS, IHF, and DnaA lead to changes in nucleoid organizations, replication initiation, and cell division

Redefining the H-NS protein family: a diversity of specialized core and accessory forms exhibit hierarchical transcriptional network integration

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