RNA‐binding protein Hfq downregulates locus of enterocyte effacement‐encoded regulators independent of small regulatory RNA in enterohemorrhagic <i>Escherichia coli</i>

Sudo, Naoki; Lee, Ken-ichi; Sekine, Yoshiaki; Ohnishi, Makoto; Iyoda, Sunao

doi:10.1111/mmi.14799

Cited by 5 publications

(9 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While these results provide an additional confirmation of Hfq involvement in the regulation of RecB translation, they do not strongly support a sRNA-dependent mechanism. This is consistent with recent studies demonstrating examples of direct regulation by Hfq in a sRNA-independent manner [106,17,104,31,90]. We nevertheless looked for potential candidates of sRNAs, using the available Hfq RIL-seq and CLASH datasets [65,46].…”

Section: Discussionsupporting

confidence: 81%

“…Based on the localisation of the Hfq-binding uncovered in the CRAC data, we further propose a mechanism of Hfqdependent modulation of translational initiation of RecB (fig. 5A) (similarly to the models of Hfq regulation suggested recently [31,17,106]).…”

Section: Hfq Regulates Recb Expressionmentioning

confidence: 54%

“…S9). Given its already high abundance in intact cells, this overproduction is very likely to sequester a large number of Hfq molecules [31,61,106].…”

Section: Sequestering Hfq Leads To An Increase In Recb Productionmentioning

confidence: 99%

See 2 more Smart Citations

An Hfq-dependent post-transcriptional mechanism fine tunes RecB expression inEscherichia coli

Kalita

Iosub

Granneman

et al. 2021

Preprint

View full text Add to dashboard Cite

To preserve genome integrity, all living organisms have developed strategies to respond to chromosomal damage. One such response is the repair of DNA double-strand breaks (DSBs), one of the most toxic forms of DNA lesions. In E. coli, DSBs are repaired via the homologous recombination pathway, initiated by the RecBCD enzyme. RecBCD is essential for accurate chromosome maintenance but its over-expression can lead to reduced DNA repair ability. This apparent paradox suggests that RecBCD copy number may need to be tightly controlled within an optimal range. Using single-molecule fluorescence microscopy, we have established that RecB is present in very low abundance at mRNA and protein levels. RecB transcription shows high levels of fluctuations yet cell-to-cell protein variability remains remarkably low. We show that the post-transcriptional regulator Hfq binds to recBCD mRNAs and down-regulates RecB protein expression in vivo. Furthermore, when Hfq-mediated regulation is perturbed, we observe less effective noise reduction and reduced DNA repair capacity. Taken together, our results suggest a post-transcriptional regulatory mechanism where Hfq fine-tunes RecB expression by inhibiting RecB translation. This fine-tuning of RecB expression contributes to reducing noise in RecB protein expression and protects cells against the toxic consequences of too high RecBCD numbers.

show abstract

Section: Discussionsupporting

confidence: 81%

Section: Hfq Regulates Recb Expressionmentioning

confidence: 54%

See 1 more Smart Citation

An Hfq-dependent post-transcriptional mechanism fine tunes RecB expression inEscherichia coli

Kalita

Iosub

Granneman

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“… 51 In vitro analyses revealed that the Hfq distal face directly binds near the translational initiation site of the grlA mRNA and inhibits its translation in an sRNA-independent manner in EHEC O157:H7. 52 It is therefore conceivable that Hfq can indirectly activate EHEC O157:H7 motility and flagellar gene expression through post-transcriptional regulation of qseBC and grlA .…”

Section: Post-transcriptional and Post-translational Regulatory Prote...mentioning

confidence: 99%

Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7

et al. 2022

View full text Add to dashboard Cite

ABSTARCT Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a human pathogen that causes a variety of diseases, such as hemorrhagic colitis and lethal hemolytic uremic syndrome. Flagellum-dependent motility plays diverse roles in the pathogenesis of EHEC O157:H7, including its migration to an optimal host site, adherence and colonization, survival at the infection site, and post-infection dispersal. However, it is very expensive for cellular economy in terms of the number of genes and the energy required for flagellar biosynthesis and functioning. Furthermore, the flagellar filament bears strong antigenic properties that induce a strong host immune response. Consequently, the flagellar gene expression and biosynthesis are highly regulated to occur at the appropriate time and place by different regulatory influences. The present review focuses on the regulatory mechanisms of EHEC O157:H7 motility and flagellar biosynthesis, especially in terms of flagellar gene regulation by environmental factors, regulatory proteins, and small regulatory RNAs.

show abstract

“…The ClpXP complex, an AAA + protease, positively controls LEE gene expression in EHEC through direct regulation of GrlR levels during the stationary phase of growth ( Iyoda and Watanabe, 2005 ). Moreover, Hfq, an RNA chaperone, together with the small RNAs MgrR, RyhB and McaS, negatively modulate LEE gene expression in EPEC at the post-transcriptional level by destabilizing the grlRA mRNA and, consequently, the expression of GrlR and GrlA ( Hansen and Kaper, 2009 ; Bhatt et al, 2017 ; Sudo et al, 2022 ). Furthermore, GrlA and GrlR also regulate the expression of genes located outside the LEE, such as the hemolysin and flagellar genes in EHEC ( Iyoda et al, 2006 ; Saitoh et al, 2008 ), as well as some non-LEE encoded effector genes in EPEC ( Garcia-Angulo et al, 2012 ), indicating that during the evolution of A/E organisms other genes were incorporated into the Ler-GrlRA regulatory network to coordinate other functions that enhanced the pathogenic capabilities of these bacteria.…”

Section: Introductionmentioning

confidence: 99%

GrlR, a negative regulator in enteropathogenic E. coli, also represses the expression of LEE virulence genes independently of its interaction with its cognate partner GrlA

Lara-Ochoa

Huerta-Saquero²,

Medrano-López³

et al. 2023

Front. Microbiol.

View full text Add to dashboard Cite

IntroductionEnteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium (CR) belong to a group of pathogens that share the ability to form “attaching and effacing” (A/E) lesions on the intestinal epithelia. A pathogenicity island known as the locus of enterocyte effacement (LEE) contains the genes required for A/E lesion formation. The specific regulation of LEE genes relies on three LEE-encoded regulators: Ler activates the expression of the LEE operons by antagonizing the silencing effect mediated by the global regulator H-NS, GrlA activates ler expression and GrlR represses the expression of the LEE by interacting with GrlA. However, despite the existing knowledge of LEE regulation, the interplay between GrlR and GrlA and their independent roles in gene regulation in A/E pathogens are still not fully understood.MethodsTo further explore the role that GrlR and GrlA in the regulation of the LEE, we used different EPEC regulatory mutants and cat transcriptional fusions, and performed protein secretion and expression assays, western blotting and native polyacrylamide gel electrophoresis.Results and discussionWe showed that the transcriptional activity of LEE operons increased under LEE-repressing growth conditions in the absence of GrlR. Interestingly, GrlR overexpression exerted a strong repression effect over LEE genes in wild-type EPEC and, unexpectedly, even in the absence of H-NS, suggesting that GrlR plays an alternative repressor role. Moreover, GrlR repressed the expression of LEE promoters in a non-EPEC background. Experiments with single and double mutants showed that GrlR and H-NS negatively regulate the expression of LEE operons at two cooperative yet independent levels. In addition to the notion that GrlR acts as a repressor by inactivating GrlA through protein-protein interactions, here we showed that a DNA-binding defective GrlA mutant that still interacts with GrlR prevented GrlR-mediated repression, suggesting that GrlA has a dual role as a positive regulator by antagonizing GrlR’s alternative repressor role. In line with the importance of the GrlR-GrlA complex in modulating LEE gene expression, we showed that GrlR and GrlA are expressed and interact under both inducing and repressing conditions. Further studies will be required to determine whether the GrlR alternative repressor function depends on its interaction with DNA, RNA, or another protein. These findings provide insight into an alternative regulatory pathway that GrlR employs to function as a negative regulator of LEE genes.

show abstract

RNA‐binding protein Hfq downregulates locus of enterocyte effacement‐encoded regulators independent of small regulatory RNA in enterohemorrhagic Escherichia coli

Cited by 5 publications

References 94 publications

An Hfq-dependent post-transcriptional mechanism fine tunes RecB expression inEscherichia coli

An Hfq-dependent post-transcriptional mechanism fine tunes RecB expression inEscherichia coli

Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7

GrlR, a negative regulator in enteropathogenic E. coli, also represses the expression of LEE virulence genes independently of its interaction with its cognate partner GrlA

Contact Info

Product

Resources

About